Marginal spot, if I thought about it enough I would call.

Usually I bet fold to get value out of mid pocket pairs that like to call down on these boards but thats only 99 & 1010 here, 88 & 77 have a boat.
So I dont mind check calling a reasonable bet - 1/2 pot to get value from a bluffing flush.

My gut feel given your reads was that it was a slowplayed overpair, scared of 2 queens on the flop that realises its good on the river. Could also be a lucky boat but you've basically telegraphed that you don't have a queen with your river check, so their 8/10 river bet isn't going to get paid off alot.

So the combination of the bet seeming large given the situation, & that it would be a strange way for 90% of hands that beat you to play I call expecting to see a busted flush/ worse hand enough to make it +ev.