Is this a bad fold?

I played this hand a few weeks ago, but it has been bugging me so I thought I would send it in.

Is this a bad fold by hero on the river.  After opponent check/shoved the river after check/calling flop and turn, I could not put his range on pretty much anything but flushes.  The only flushes I am ahead are 2,6 and 2,5.  I try to tell myself when playing 1/2 that opponents do not bluff that much (that has been my experience in reviewing hands I have lost in the two years I have been playing 1/2) so I folded.  Unknown opponent but I do not think tough or tricky.  Good fold or giving opponent too much credit for a flush?  

Thanks.