Brakes Problem

my 98 S-10 is messed up again. Had a problem last fall and ended up being the master cylinder. Since being replace, no problems.
Yesterday on a short ride to the store, my brake pedal went to the floor. Thought that a line had failed at first and then I thought maybe that the new MC was defective. By the time I got home, the brakes were fine. Nice high peddle and no leaks

BUT

the right front caliper is grinding pretty good.

Maybe a pad broke?

Take the wheel off and check it out.

Take the wheel off and check it out.

thanks for your help