I find that I tend to go through phases with game design, where some days I am content to grind the shit out of a project for 12 hours straight, and other days I can only muster a few small tweaks or code changes, mainly due to working a long and tiring job. I'm bad at art, so I don't know if the same would apply to what you do, but with hobbies in general I think it's fine to have times where you only feel like doing a little bit.
I think the alternative is that you push yourself too hard and get burnt out, and that's worse. So no, I don't think you're doing anything wrong.
AlfaFranek
You are at point where you just enjoy creating art in which time just flies by and since you value it more, the other activities seem less important than before. As of right now, I'm not that kind of flow, but I have seen quite a few people being in exact situation you are here right now.
I think it's normal.
Mazooe
Thaniks! I didn't want to llok like I'm just slacking off, I got real life things to work on and I don't like leaving a drawing half done, I love to dedicate an entire day to getting details right, I just feel I need something that doesn't require that much mental strenght (playing video games, listening to music etc,) but I'm assured I'll come back with a drawing when I feel less "forced"