Not only his mouth and face, almost all Harry’s clothes have some different sized dark crimson stains. Harry clearly remembered that there was no paint in the cupboard. So the boy was questioning himself, where are those from. In his thoughts the boy bowed down his head, trying to find a can. And just a bit down, on the floor, there were some light sticks. Harry would say that those are white, but as his eyes were highly adapted to darkness during the last few days, that's why all colors are a bit biased. The boy has a very bad premonition about those "sticks".