You probably bumped the leaver or just have it misaligned when you put the wheel in.
If you bumped the leaver and pushed the pads in too far you will have to pull the pads out and push the pistons in to reset them (I use an appropriately sized spanner ring end or sometimes a tyre leaver will be ok).
If it is just misaligned look down the top of the caliper and try to align it by eye so there is even space either side. You can also do the loosen the caliper bolts, hold the brake then re-tighten them, I find using my eyes works better than pushing in the brakes.
hope this helps