[ QUOTE ]
I don't know if this is more unlikely, but in a limit hold em game I once flopped set over 2 sets with an overpair out there as well.

[/ QUOTE ]
Your hand in Hold'em is way, way, way, way more unlikely then the OP in Omaha.

Not that you asked anyone to calculate it but I'll bite.

I'd estimate 6^3 for the three flopped sets or about 200 times less likely. Hard to estimate the relative probability of an overpair in Hold'em vs. a 4th set in Omaha but I doubt it makes more than a 2 times difference up or down. So I'd say your hand is 100 to 400 times less likely. Wow.