O/S/F brake caliper

[Derekco]

Hi has anyone had an issue with the o/s/f brake caliper sticking on ,reason I ask is the piston slides in and out easily also the guide pins are free although the top pin was tight to come out  , this I thought was the reason for the caliper sticking on , after freeing it off I took it for a gentle run about 5 miles O/s caliper hot n/s caliper cool .Only thing I can think off is the caliper piston is sticking at a certain point ie the current pad thickness ( pads are brand new with about 2200 miles on them any thoughts would be appreciated. Derek