Interesing coin, looks and weighs as a nickel quarter should. Doesn't look non-magnetic at all. I have a couple of non-magnetic quarters from the 70's. Unlike yours they are both seriously underweight and dull looking.
"Dipping" is not considered cleaning... -from PCGS website
It is within tolerance of U.S. Nickel planchet and U.S. nickels aren't magnetic. However, doesn't appear to be any missing design from being struck on a smaller planchet and U.S. nickel planchets shouldn't be hanging around at the mint.