probability of hands clashing....

So I was playing 1-2 NL at the Taj yesterday, and I held 99 in the small blind. To make a long story short and to spare you all the intricacies of how we got there, on a flop of 988, I was all in and got called by a guy with poket 8's for quads. What are the chances of this happening? It's got to be astronomical. The chances of flopping quads is like 500 to 1 at least, and the chances of another guy flopping top boat on the same hand has got to be astronimical. Anyone?

Ryan