Diaper party question

Brittany
So we just had our diaper party and received some great diapers :) however I don't know the protocol...do we send thank you notes to the guys that brought diapers? In return for the diapers they got food and beer...and we said thank you to everyone before they left too...just wondering because I want to make sure we are following procedure here and not being rude...
Thanks ladies :)