I may be going down a similar road in my 1995 GMC S1500 (as Jamie, not the OP's truck). Driving down the road yesterday in a straight line, heard two small thumps from the front of the truck and the ABS idiot light came on. I really don't think I hit anything. I can't see anything wrong under the truck, no missing wires to the brakes. Other than ABS is not working it brakes fine. If I knew it was just ABS I'd be inclined to ignore it, but the thumps have me a bit worried. It has a lot of rust too, but nothing vehicle killing yet.
There are a few other things it may need such the Sears tire monkey's think my pitman arm is loose. Between brakes and the possibility of losing steering... I think I'll get it looked at before I get it on the highway.
To the OP, fire is always a good answer.