did you move your stance angles at all?
Did you injur it before and now you're just reaggravating it?
Are the new boots harder to get into? do you have to tweak your ankle to get into 'em?
If you're using Hyperlite claws on your board, check to see if they're tight, sometimes they come loose and your boots will slip changing your stance angle and you won't even know it.
My hip used to bother me until I fiddled with my stance a little bit.