Working for a dealership it is absolutely imperative to keep your own logs of stuff. Try to document what conditions it was under, did anything feel different , etc. If drivability does change push for an appointment earlier.
Loss of power/acceleration is tricky to diagnose and if no codes were stored it makes it even tougher. Recreating those intermittent concerns are a bitch for us in the service depart, we hate it as much as our customers.