Brake Grabbing

Well I noticed my brakes started grabbing a few days ago. Everytime I was about to stop at a slow speed, it stopped for me. So after driving for a while I checked each rotor to see which one was heating up and sure enough the driver's side front rotor was hot. When I jacked it up I could hardly turn that front wheel, which would normally spin rather easily. Took the caliper apart, pushed both pistons back in completely, put it back together and luckily everything is back to normal. Apparently only one of the dual pistons was sticking (see pic) I've seen this before and part of the problem is the fact that MD salts the crap out of the roads. BTW the truck only has 24k.