A sore throat is an irritated throat, usually caused by irritation to the tonsils.
Good thing I don't have those tonsils anymore :D
On-Topic: You probably should get it checked out if it's seriously giving you pain, and it's been persistent. If it's something a good nights sleep hasn't healed, it probably needs to be checked out. And, even if it doesn't give you pain, (Like, just an uncomfort) then I'd get it checked out at the doctors due it lasting longer than a day.
