I have a hard lump on my upper gum and had the dentist look last week. She said it's bone, but it seems to be bigger this week. Is that normal?

Needs more info. This situation requires a clinical exam and possibly X rays. You really need to have it reevaluated by your dentist.
Exostosis. Yes, it is normal. The exostosis (bony protuberance) can grow. If it becomes bothersome, it can be shaved down under local anesthetic.