What to do if you suspect a player is cheating?

[SiyfkA]

Heres the story, I was playing over at Pokerstars $0.25-$0.50 NL today and there was a player there that seemed to be playing every pot, calling every raise with rag hands like 82s, 73o/. But somehow he ended up winning about $100 over about 3 hours of play. After finally leaving after trying to beat this donk several times, I decided to check Pokertracker for his stats.

In 117 hands he never raised once preflop, but called a staggering 87.18%(!!) of the time. Flop AF was 0.27, Turn AF was 1.53 and River AF was 4.00. He won 44.34% of the time.

Am I being paranoid here? Is this kind of donk play common at these stakes and he just got lucky?