The point is that you can't really tell if it's no problem on gingerbread, because it happens in random intervals. Maybe on gingerbread you were just lucky.
Anyway, this is not normal.
Before your phone really dies, I'd install a stock gingerbread rom on it and update to Ice Cream Sandwich through kies.
If it happens on an original Samsung ROM, return it.
You don't want such a problem after you've lost warranty.
Maybe it'll become even worse in future, so better get a replacement.
Quem vem la, sou eu, Quem vem la, sou eu,
Berimbau bateu, Capoeira sou eu