First,make sure your wheels are mounted properly. This prolly isn't the issue,but it always helps to eliminate the simple things first. Next,what kind of discs,hydro or cable? If they're cables,it sounds like the pads might be adjusted a bit close. Just back them off a touch and you should be alright. If hydros,it could be either the calipers aren't centered properly,or they're just not high end. It's not uncommon for low to mid grade hydros to drag a touch;my old BBU used to do it sometimes after a hard stop and it would quit after I hit a good bump. If they're hydros,have the shop take a look at them to make sure they're centered properly and that nothing has gunked up the seals to prevent the pads from fully retracting.