Depends...I have two teeth where food gets stuck in between there all the time. the contacts are tight but it'll be sore sometimes just like yours sounds. May be nothing, especially since you had it checked out in Jan. or whatever. Do you have any fillings between those two teeth? Meats, beef jerky, etc get jammed down into your gums, and if not removed fairly soon will cause some swelling and tenderness in the gums. Some of it is from trauma and some from bacteria around the food debris. Just make sure you're flossing between your teeth everyday and the soreness will usually go away.
Could also be an open contact....meaning those two teeth aren't completely touching, allowing more food to be pushed down in between those two teeth.