Taylor Swift Poses with Celine Dion After Grammys AOTY Onstage SNAFU

Taylor Swift won Album of the Year (again) at the Grammys, but weirdly ignored the musical icon presenting in Celine Dion -- even though ... she paid her respects backstage, it seems.

Rare misstep for Tay Tay, who's usually on point ... but on Sunday night, she kinda screwed up -- at least in Twitter's eyes, anyway -- when she paid little to no attention to CD who announced her as the winner for AOTY ... which was a big deal for a lot of reasons.

It was the final award for the night -- and the largest prize at the Grammys, period -- which is why it was such a remarkable moment to see Celine come out to present it in person.

Of course, she's very publicly battling Stiff-Person Syndrome -- and has stepped away from the spotlight of late -- so for her to do this was notable and moving, especially since she appeared to look relatively healthy here ... something the audience met with a standing O.

Fast-forward to Taylor being named the winner, when she ran onstage with her collaborators -- plus Lana Del Rey -- and looked so overcome with emotion that she totally downplayed Celine's presence ... simply taking the statuette from her without so much as a nod.

Indeed, it came off as quite rude -- you could tell Celine found it odd as well -- and the Internet unloaded on Taylor for what they perceived as a major lack of respect/reverence.

It would appear Taylor and/or team caught wind of this backlash quickly -- 'cause not too long after ... a photo of the two posing together (and looking cozy) backstage surfaced, which a ton of outlets then posted without much description or captions. Coincidence much?