Did you push or turn the piston in? If you pushed it in and it was easy that doesnt necessarily mean you won't have a frozen caliper. The way you adjust the position of the piston is by screwing it in or out (rightie tightie, leftie loosie...as usual). Take the caliper back off and screw the piston in just until when you put it back on, the wheel can turn relatively freely, but not so much that you can wiggle the pads in their place when everything's all back together...worst case scenario you screw it in too much and it'll take a couple of miles to adjust itself properly.