Raised on turn after I pick up draw, I 3bet

[efficacy]

pstars 5/10 6 handed

villain is like 21/17 over smallish sample, no history with this guy.

preflop: villain opens in CO, I call in BB with QJo and we go to the flop HU.

flop K72r: I c/r... he paaaaaaaaaauses, and finally calls.

turn Tr: I bet, he insta-raises and I insta-3bet.

Isn't his turn raise a rebluff or free showdown raise a good portion of the time? Or should I be giving him more credit since we have no history?