Rodney is right on. It's the servo. Back a few years ago, you'd actually buy "reversed" servos that worked in the opposite direction. This was back before servo reversing on all channels was the standard for transmitters as it is now.

Another funny is that no one agrees on channel numbers either. Futaba and JR don't agree on what control function is 1, 2, 3, or 4. I switched a plane from a JR to a Polk transmitter, and I had to actually unplug and rearrange the servo leads in the receiver. Oddly enough, I didn't have to reverse anything though.

Always checking and re-checking is a good idea. Not just a control wiggle, but making sure they go the right direction and seem to move "normally" is a good thing. If you notice a change from flight to flight, like something moving more slowly than it should, it might save your plane.