Acting normal now??
Usually, suhc sulkign is a sign of unhappiness(say, his best friend died, or maybe a move form oen tnka ot the other)
I'd just wathc him for boredoem , be sure he's eatign etc.
And if you havnet already, a bal or somethign else would make somethign for hte oscar ot do when its bored.
Good Luck!