After 2 couple hundred mile trips this week I had some wierd issues. Every time I run more than about 75-80 miles down the interstate my low tire light comes on. It doesn't ding at me like a low tire the light just comes on, I check the tires and they are all dead on at 42psi. I stop and restart the truck and it shuts off for another 75 or so miles. Driving in town it never comes on. I am guessing it is a signal problem on one of them or perhaps the little internal batter is going dead. Any ideas?