Ray Allen isn't the most beloved figure in Boston Celtics history.

Though he was a key member of the group that won championship No. 17 in 2008, Allen left the Celtics for the rival Miami Heat in 2012, leaving a sour taste in the mouth of many of his former teammates, not to mention the city of Boston.

Five years later, it looks like the future Hall of Famer is fed up

Allen, who turned 42 on Thursday, spent some of his day responding to Instagram users who commented expletive-laced rants and snake emojis on a "happy birthday" picture posted by a Celtics fan account.

"Y'all need to get over it!!! Where were you all when the team tried to trade me. It's a business, we go where it's necessary just like you all do in your jobs!!!! I will always be a Celtic no matter what any of you say. Get over it!!!!"

Allen continued: "Oh and thank you everyone for wishing me happy birthday!!!"

The comments, which have since been deleted, were captured by various Twitter users.

This is hardly the first development in the Allen-Celtics saga. In May, Allen wasn't invited to a Celtics reunion — which featured Kevin Garnett, Paul Pierce, Rajon Rondo, Kendrick Perkins and Glen Davis — that took place on TNT's "Area 21."

During the segment, the former players discussed Allen's decision to leave Boston.

"The situation with Ray is very sensitive," Garnett said on the broadcast. "I think that when we all talked about doing this reunion, we were talking about guys that we consider loyal, part of this group. Just being honest, my two cents, man, when Ray decided to go to the Heat, I feel like he moved on. He went to pursue another ring, he got another ring, shoutout to him, and that's it. ... It was all Celtics invited to this."

Pierce added: "I was initially hurt by the whole way everything went down. ... I just felt like we should have had a conversation and I think it would have settled over a little bit more. I don't think we would have been as salty. Even though it was Miami, we hated them. We hated Miami, that was our rival, we were going at it, LeBron, all them. I just think if we had all talked about it, it would have been a little different than it is now.

"Now it's uncomfortable. I haven't talked to Ray in some years now. It's different."

The morning after the reuinion, it appeared Allen responded with a not-so-subtle jab on his official Facebook page by posting a picture of himself (in a Heat uniform) fighting through defense from Rondo, with the caption: "The power to push limits."

Later in the day, ESPN's Rachel Nichols said Allen's publicist told her that Allen's Facebook page was hacked, and the page was later unverified.

PHOTOS: Ray Allen through the years