After a getting a flat on Tues I finally retired my old tires and threw on a pair of Schwalbe Marathon Supremes. Had my bike upside down for the process. When I finished, I noticed the rear wheel brake noticely had more give than before. I have the squeeze the lever all the way to brake now.

I can't figure out why how this could be. I've never had to do anything with my brakes since buying the bike nearly 2 years ago. Any ideas?