Well let's see if I can calculate the odds:
You each have two hearts. That means 3 * 2 = 6 hearts are out. There are 13 hearts, so 13 - 6 = 7 hearts left in the deck.

Chances of each flop card being a heart, multiplied together:
7 hearts / (52 cards - the 6 hole cards = 46 left in the deck)

7/46 * 6/45 * 5/44 = ~0.2 percent.

Note: NOT 2 percent. 2 TENTHS of a percent. So... it's fated to happen twice in a thousand trials. Once in 500 such scenarios (this is given all three of you have suited hole cards of the same suit, and no other information is known).

It seems like just a freak incident, though, not a con. What do you think happened? That the dealer was distracted enough to let a rigged deck get placed on the table? And that the new deck was left unshuffled and uncut with no protest by anyone at the table? Odds are, it's all in your head. My condolences on having the third-to-nuts (o wait fourth).