I didn't think much of it, but after two weeks, my newest betta (The Tiny Yellow Submarine) is still very shy! Normally after a few days, or a week at most, my bettas are already swimming up to the glass and begging for food. However, this guy is still darting behind his heater or under his plant. And when he does feel confident he slowly creeps up to my hand. I don't know if he's sick, but he does seem unusually lethargic and shy.
His water is heated at 80 degrees and he has half a ten gallon all to himself (He was originally in a 2.5 gallon tank, but was hitting his head a lot when he freaked out).