yea it sounds like the piston is sticking....just pop it out and like u said de- and re-lube it and get new pads and see if it works then....this can also happen if you dont compress the piston when changing the pads.....not saying you did that or anything, but shit can happend.....use a C-clamp witht the old pad on the piston side and tighten the C-clamp till the old pad is flush with the calaper and then put the new pads on and get everything bolted up and pump the breaks with the car off till they get really stiff.....then drive it around for a bit and see how it works.......


Miles