I do have times that I am "not feeling it". Not sure if that's what you mean or not. But with me, my "not feeling it" has more to do with what's going on in life... work has wore me down or I am worried about my kids or family or too much other stuff going on. I just don't sew or worry about it when I am in that mood.
I sure wouldn't worry about it at all if I were you. Sew when you want to - if you don't want to there's nothing wrong with that.
Not that this applies to your situation... but I have learned that when "life" has kicked my butt and I am not feeling anything... if I give myself a little push to the sewing room its always worth the push ha ha. The sewing purges all of the ugly out of my head and I get refreshed
but everyone is different