Perfectionism
LabPet,
My humble and probably severely flawed perspective:
Human beings abhor those who are different. I've found that trying hard to be appreciated, or liked, or tolerated, only seems to make matters worse. It seems that the more you care about fitting in the less likely it is you will be accepted.
Plus, the work place is competitive, so your natural 'extra effort' might be perceived as an attempt to move past your peers, or even your boss. This would create some animosity. Some people put forth an extra effort to get closer to their supervisor so that they can get special treatment - this clearly isn't what you are doing, but it might look that way to someone else. So your supervisor may feel that she needs to keep her distance from you.
Your hard work is most probably noticed, very likely appreciated, and hopefully rewarded.