I thought about throwing in Sergei saying "Kids can be so useful.", but really I think an unmentioned joke is being made.
Anyway, I noticed this just this past week and it really bugs me a lot.. I tried to keep the shading and highlights simplistic when I started this arc, but eventually I found out a few tricks here and there and totally started using them in the comic.
Forgive me for referring to a TV Trope once more, but I've noticed my own level of Art Evolution even just within this one story arc. When it comes to the comic, I HATE it that I'm learning new art tricks and then unintentionally applying said new things mid-story arc. The..ahem.. overall story (yes a laughable notion).. has suffered from inconsistency as it is so I would enjoy some kind of uniformity in art style too. I was hoping to maintain a steady style throughout , but unfortunately that's not happening.
I just really love shading and highlights.. When a picture starts to show some level of dimension, that's just the best part to me. So I go overboard I reckon. Can't help it. =-0