I've had periods of time when I've suffered from this, Kevin. Not too bad right now. At first, I thought it was linked with my GERD. Then, there was a suspicion that I had lupus - this was before my joint problems really got going. I had a lot of mouth ulcers with the generally sore mouth and tongue.
Now, I think it may be sjogrens or GERD - not really sure. I'm waiting to see if it gets worse with the methotrexate.