Transmission Light Comes on after being in the mountains?

I am on my way home from the mountains and my "overdrive off light" came on followed by my "trans temp" light. After this I notice a sound coming from the transmission like a light grinding. The truck does not want to accellarate and jerk some. However, after the truck sat a few minutes the "trans temp" light went out. A mechanic at a tire store said that it could be that my transmission fluid had gotten hot and bubbled up.... what are your thoughts? I am nearly 300 miles from home and real worried about this.