your price relative to everyone elses average price can affect your demand, so if the average drops down you may lose a few passengers because you lost some of the little boost you had before. if the average goes up, you may (possibly not visibly) gain a little bit of demand.
So. Likely in this situation, something changed to lower the average ticket price on the route, hurting your demand a bit and thereby costing you a few passengers.
mmm... nuances.
