torx bolts suck, suck, suck...
if I was too subtle about it, let me repeat it - they suck hard...
As I took each torx bolt off my jeep, I damned it to hell as I threw it across the yard. Cheap torx wrenches suck too - they snap off if you blow on them hard or use harsh language. Break down and get Craftsmen or something similar, and impact wrenches help out as well.
I would almost bet a whole 15 cents, that there is rust in the thread holes -hit them with wd40 and run them in and out, in and out a few times - I know, it makes me excited too. Then, clean it out with carburater cleaner and then a thin coat of silicon on the threads helps out sometimes
In any case, just like everyone else has said, replace it with hex bolts, they might stick out some, but they look more manly...