Golang mgo大于和小于时间戳

I'm trying to query a timestamp that is between two other timestamps. I've got this simple function:

func (e *EventService) GetEmployeeEventsBetween(employeeID string, start, end int64) ([]Event, error) {
    var retrivedEvents []Event
    if err := e.c().Find(bson.M{
        "employee": employeeID,
        "start":    bson.M{"$gte": start, "$lte": end},
    }).All(&retrivedEvents); err != nil {
        return nil, err
    }

    return retrivedEvents, nil
}

Now according to that function the query should only return "events" that start date timestamp is greater than the start timestamp passed in and less than the end timestamp passed in.

However let's say the db has 3 events each with these start dates:

1474290000 1474389000 1474463700

Now lets say I pass in a start param of 1474462800 and end param of 1474491600 I would expect that function would only return 1 "event" which would be the one with the 1474463700 timestamp however it returns all of them. Pretty much no matter what I pass in as my start and end params it returns all the items in the db

UPDATE:

If I log .Explain() this is what I get back

bson.M{
    "queryPlanner": bson.M{
    "plannerVersion":1, 
    "namespace":"hairbuddy.events", 
    "indexFilterSet":false, 
    "parsedQuery": bson.M{
        "$and":[]interface {}{
            bson.M{
                "employee": bson.M{"$eq":"57c36bdfe5b07e10ae5526ee"}
            }, 
            bson.M{
                "start":bson.M{"$lte":1474491600}
            }, 
            bson.M{
                "start": bson.M{"$gte":1474462800}
            }
        }
    }, 
    "winningPlan": bson.M{
        "inputStage": bson.M{
            "stage":"COLLSCAN", 
            "filter": bson.M{
                "$and":[]interface {}{
                    bson.M{
                        "employee": bson.M{"$eq":"57c36bdfe5b07e10ae5526ee"}
                    }, 
                    bson.M{
                        "start": bson.M{"$lte":1474491600}
                    }, 
                    bson.M{
                        "start":bson.M{"$gte":1474462800}
                    }
                }
            }, 
            "direction":"forward"
        }, 
        "stage":"LIMIT", 
        "limitAmount":40
    }, 
    "rejectedPlans":[]interface {}{}
    }, 
    "executionStats": bson.M{
        "totalDocsExamined":3, 
        "executionStages": bson.M{
            "restoreState":0, 
            "isEOF":1, 
            "invalidates":0, 
            "inputStage": bson.M{
                "restoreState":0,
                "direction":"forward", 
                "stage":"COLLSCAN", 
                "executionTimeMillisEstimate":0, 
                "works":5, 
                "needYield":0, 
                "nReturned":1, 
                "advanced":1, "isEOF":1, 
                "docsExamined":3, 
                "filter": bson.M{
                    "$and":[]interface {}{
                        bson.M{
                            "employee": bson.M{"$eq":"57c36bdfe5b07e10ae5526ee"}
                        }, 
                        bson.M{
                            "start": bson.M{"$lte":1474491600}
                        }, 
                        bson.M{
                            "start": bson.M{"$gte":1474462800}
                        }
                    }
                }, 
                "needTime":3, 
                "saveState":0, 
                "invalidates":0
            }, 
            "stage":"LIMIT", 
            "advanced":1, 
            "needYield":0, 
            "saveState":0, 
            "limitAmount":40, 
            "nReturned":1, 
            "executionTimeMillisEstimate":0, 
            "works":5, 
            "needTime":3
        }, 
        "allPlansExecution":[]interface {}{}, 
        "executionSuccess":true, 
        "nReturned":1, 
        "executionTimeMillis":0, 
        "totalKeysExamined":0
    }, 
    "serverInfo": bson.M{
        "version":"3.2.7", 
        "gitVersion":"4249c1d2b5999ebbf1fdf3bc0e0e3b3ff5c0aaf2", 
        "host":"rodrigos-MacBook-Pro.local", 
        "port":27017
    }, 
    "ok":1,
}