Tournament Team Play

In a home Omaha/8 limit $60 no rebuy 24 player tourny I made the final table. There were three players who were close friends and would not bet/raise each other. This was more than obvious as repeatedly they would bet/raise till only these 2 or 3 were left in hand, then they would turn hands up and say "no more bets,burn and turn the rest of the board".They finished 1,2&3.(me 4th).It payed 5 places so I got $240.

I feel their play was unethical or may be considered cheating.Am I right or is it just sour grapes?