After reading up on sticky calipers... I think it would be normal to see one side doing it, but both at the same time, out of the blue, seems odd.
Stranger things have happened though... yesterday, I put the car on stands, spun the wheels by hand and both fronts seemed like the pads were rubbing pretty good. After bleeding yesterday and lubing the slides, I put the wheels back on and they spin more freely. In an hour or so, I'll go fire her up, go for a cruise and see what happens.
If I still get caliper grabbing issues, I'll crack the bleeder to the caliper that is sticking and see if I get movement from the piston. I won't rule out moisture in the fluid, but I have bled the entire system in the last year and went through the procedure yesterday (made sure there was a good stream coming, maybe 6-7 times per wheel, starting at pass, rear.) and had to fill each reservoir to top them off.
David, I see what you mean about the little rod/valve on the combo valve. It wouldn't have anything to do with the calipers grabbing at all, but good to learn just the same...
NOTE: I just took the Camaro out for a 20 mile cruise and it ran like a champ and NO sticking caliper issues. I think bleeding the brakes well, in combination with lubing the slides, did the trick.
Hopefully they work well for a while now.....