Are you 100% sure it's not the nut? That exact same thing happened to a guitar of mine a few years ago, a tiny bit of filing it out took care of the problem.
If it IS a fret... And I would think twice if you haven't done this... I actually fixed one a few years ago. The neck was straight, intonation was perfect, action was as desired, just one protruding sonofagun. I folded a towel, laid it on the fret, and hit it a few times with a hammer.
I don't readily recommend doing this unless you are super confident with your setup assessments, which can be learned easily, and you have diagnostic experience.
A slightly less invasive method would be to put a dehumidifier in the room with the guitar, but that is assuming you keep it on the stand and not in a case.