KK 1/2 nl hand

[cracker9521]

A friend played this hand and we have been discussing it for a while would like some input from you guys. This is just starting the second orbit at the table so no reads on villian. Hero gets dealt KK in mp2 and opens for $20 (15 or 20 is very standard open in this game) only called by CO. Flop comes JQ7 rainbow. Hero leads $25 and is called. Turn is a 3 completing the rainbow. hero leads $35 and is called. River is a Q hero checks. Villian puts hero all in for an additional $100. Hero..... I was saying that he should have pushed on the turn since a pot size bet would have commited him anyways. Thoughts please?