No, hamsters occasionally get greasy fur. You can offer your hamster a sand bath using chinchilla sand (not dust!) or sanitized play sand to help wash herself.
I just had a ham turn into a little spitball on and off for a day. Pretty disconcerting...
Very high humidity and after that day? It was like he went from being a young kinda Longhair to a full blown LONG HAIR....but he was fine. Yup , it looked like greasiness or sweat to me too!