Hm... could be a raised fret... or a raised tongue... Either would cost more to fix than the guitar itself... If your guitar has a one piece maple neck... I would bet on either of those as a possibility... rosewood slab necks are less succeptible to rasied frets... but more succeptible to raised tongues... But it could just be that your neck is settling in the pocket... causing it to sit a little differently than it normally would. I suggest you take it in to get the strings changed by a tech... and tell them what your prob is... most likely they'll fix it for you... put your new strings on and have you all ready to go.