My Rear Differential Oil temperature indicator came on yesterday. I pulled over and put the car in park, light went out in about 2 minutes. I was towing a lightly loaded trailer and had been for about 60 miles. I had towed the same trailer with a heavier load (500lbs more) for 120 miles the day before with no issue. After the light went out I towed for about another 60 miles with no issue. Air temperature was about 90 F. Any suggestions?