Albus was put in Slytherin. The sorting didn't make a bad choice because maybe Albus could raise the Slytherin House liking considering everyone in the Harry Potter world be hating on them. So with a Potter in Slytherin it could help the house.
Great chamber musicians communicate and react not just by playing the correct notes, but through eye contact, body motions, sniffs, winks and all sorts of non-verbal cues.
