1997 Tahoe ABS brake problem

I am new to this site,and my questions may have been answered before, but here goes.I have a 97 4WD Tahoe.that had 17,000 miles when purchased. At around 75,000 miles the ABS brakes began to act up. When slowing to a stop the ABS would activate at around 3-6 mph. I took it to a mechanic and he scanned it and said one of the wheel sensors was out of calibration, but not sure if changing it would help. I ended up taking it to a Chevy dealer who said I needed both front hubs replaced because there was play in the bearings and that is what was being sensed by the wheel sensor. $800.00 later everything worked fine. Fast forward to 118,000 miles. Brakes still worked fine. Truck sat for 6 months in the garage while in Florida. Upon return home, found battery had gone flat. Charged battery. Upon using the truck, the brakes are again acting up. Not every time, but once in a while. Do I need to replace hubs again or can the problem be in the sensor itself? Can sensors be checked somehow? I can't imagine front bearings wearing out while sitting. Any help with this ongoing problem would be greatly appreciated. By the way, no ABS problem light ever comes on. :screwy: Thanks
Tom