Weddingbee boards

My fiance recently served as the best man in his friend's wedding, and the groom gave all of the groomsmen a gift for participating on the day of the wedding (this past 8/28). However, my fiance and I both bought the couple a wedding gift, which was clearly marked from the two us, and it was delivered to them around mid-late July. We haven't received a thank you note for the gift yet, and I know that the standard three-month window hasn't passed yet, but I was curious to know if a couple needs to or should send a formal thank you for wedding gift from a member of their bridal party, if even the bridal party was given a "thank you for being in my bridal party" gift. What do you guys think?

@ Pia - I'm not "worried" about it per se. Though, this guy is going to be in our wedding party next summer (and even though we aren't having a MOH or best man, he is kind of the closest thing to best man), so I'm just keeping it in mind. I'm just curious about it from an etiquette standpoint really. I mean my fiance has only been a groomsman once in the past, and we did get a thank you card from the couple for the wedding gift we sent them. But I otherwise have no idea if it's proper to do so or not!