Should a small gallbladder polyp cause constant pain?

No: Gall bladder polyps should not cause any discomfort unless the are big enough to block the outlet to the gall bladder

Not usually: There are cases where a polyp might get stuck in the cystic duct outlet or otherwise be squeezed by the gallbladder and cause pain. But I would look for another cause before having gallbladder surgery. Course if your polyp is big or growing quickly you should have gb out to make sure polyp is not a bad polyp , regardless of the pain.