I got a leopard gecko from a friend of mine (she could no longer take care of him), he's almost 4 years old. Though I've had him for just over a year, he still hasn't warmed up to me. I have tried to pick him up and pet his head on a regular basis, but lately when I have tried he turns his head really quick and bites my hand. It doesn't hurt, but it startles me. He has bitten me 6 times, and I am ready to call it quits with even trying to pet his head. Is there anything I can do???