It happened to me this week. Usually, every time I sit on a kit, it instantly brings a smile to my face. What with the build up to the show, days of testing/tuning/head changing, the show itself, & everything else involved, I'm drummed out. I turned up at band practice Monday night, & just couldn't muster the usual joy, & it showed in my playing too. I'm sure it's a short term blip, maybe age related too, but especially you pro's, does it ever get you like that?