I worried about our chi's ears too. They didn't even start to stand til around 4 months. Then it was one up,one down. Then the other up and the other down. And then they stood and flopped at the tips. And finally around 6 months of age he had beautiful straight up strong standing ears. I guess I really wouldn't worry til he's about 6 months old.
I wouldn't worry to much right now. The ears are going to do some weird things the next couple of month while he is teething(spelling?). Usually around 6-7 months will give you an idea. I had one when I was (alot lol)younger whos ears didn't stand up until he was a littl over a year.