Definitely not just you, I feel the same way.

For me it has to do with the level of competition I'm adjusted towards. I don't ever think I can play all that well if I don't get to play Snudge or Logic in the last day or so. If I'm not forced to really step it up, then I feel like I "settle" and then develop bad habits.

The only way I get out of it is either finding that steep competition somewhere, or set goals independent of winning for me to accomplish that way I can push myself. Like hit a certain speed, only touch the ground with my hands a certain amount of times in a game, etc.