Mendes and Baldwin's friendship appears to have started long before the Met Gala, though.
The two first interacted on Twitter in 2013, and the conversation was reportedly more than a friendly one.
Shailey speculation slowly started dying down from that point on, but then the 19-year-old posted a picture of himself and the 21-year-old model last week without any explanation and sh*t started hitting the fan once again.
Mendes is performing at the Billboard Music Awards on Sunday.
And if he brings Baldwin with him to the ceremony, fans will probably speculate about them being more than friends.
" The conversation may not have led to a romantic relationship, but it may be what sparked their friendship.
Since then, Baldwin and Mendes have supported each other over the years, and according to some reports, they've been caught engaging in PDA, too.
And if he and Baldwin want to keep things private about who they're dating — or not dating — that's totally their right.