Brake info....input please...

The missus' came home tonight and said the brakes were grinding on the GTP.
Her dad put brake pads on the front not too long ago and said "next time turn the rotors"... I went to take it for a ride and made it less than 50 feet before turning around and parking it. Went to Autozone and bought new rotors and pads......Driver's side outside pad was fine...inside pad was grooved about 1/3 from bottom. Passenger side outside pad was perfect....inside was all "metal"...no pad left......Now the piston on the driver's side went in fine with the c clamp....passenger side was a little tougher but went in....drove it around tonight and all is fine......
I am thinking maybe rotors were "grooved" or warped too bad to begin with or maybe piston on passenger said froze.....any ideas or experience yourselves...
Thanks guys,
Will

Anyone seen this before?

JT, think your right on it........the piston on the passenger cal. was a lot harder to get in ........I'll check it in a few weeks to see how the pad is wearing and replace cal. if needed.....thanks guys