It was a comment about the point, not a call. Calls happen immediately. Server’s partner can call it out, but isn’t required to. Read The Code carefully and note my comments about best angles to make a call.
The only sketchy thing was the comment, maybe innocent or maybe gamesmanship. Either way, it was not intended as a call and no one being reasonable that knows The Code being would insist it was.
I’ve been playing competitive tennis for 50+ years and have never once seen a player play a first serve then ask the opponents if the serve was in after the point was over with the intention of it becoming a fault, LOL. That’s essentially what the OP did, two bites at the apple.
Unless the receiver or partner call it out, a serve is in. We all know server’s opinion is irrelevant on first serves unless they choose to step in and overrule against themselves, which is not required by the code. It’s also clearly not what the opponent was trying to do in this case.
If it were a second serve and the opponent made this comment, OP could have rightfully claimed the point under the rules (though being legalistic is not how you make friends on court).