A couple of thoughts:
Did you seat the piston in the caliper? If so, you just need to pump the pedal a couple of times to get the fluid back into the caliper and push the piston out to where it self-adjusts.
Even if you did not open the lines, moving them around enough could cause some air to get into the system if you have weak hoses, etc. If the above doesn't work, and you bleed the system and the pedal returns to normal, I would advise caution. This would indicate some kind of weakness in one of the lines somewhere, and you could experience a total brake failure at the wrong time. Carefully inspect every part of the brake system.
