Telling them to stop is is not necessarily a negative reaction and for some people is part of the process of getting to acceptance. Who knows, maybe OP is now ready to not react "negatively" because he has finally reacted after keeping his annoyance pent up all this time.
Well this topic certainly has gotten a lot more traction than I anticipated. I appreciate all the thoughts on the matter from everybody and respect the many views on it.
With that being said, just like everybody else, I have thoughts of my own.
Given this was Sunday night and I've had time to reflect & see answers here, I'm inclined, of course there's two sides to every story in that maybe he feels differently, to feel this isn't a big deal and I've said my peace. So in a way I suppose I'm agreeing with Next Level's comment of either choice was fine. (if others more or less said that, didn't mean to leave you out.)
I'm the type in a competitive environment, I'll just dish it out as much as the next guy wants to. The opponent gets to help dictate where we take this. But I won't just sit there and take it. That's for sure. While I still think it's bad form, again I see no difference from a comment like this to choing on someone's service error (Yes! Lets go!, etc) all the same thing, then if you do it to me? You bet I'll do it to you. Fair is fair.
Having said that, tone can't be conveyed in my OP but I really did try to as politely ask him not to as I could have. I don't think it got in my head or effected my gameplay going forward. I just thought I'd finally mention this thing I find bad form. Truth be told I don't want to be the type to make some sarcastic joke when he Fs up on a serve. "oh nice serve." "Thank you may I have another." etc. Not my style. But if he's doing it to me, again it's coming right back to him when it's my turn.
But I said my peace to him. I'm sure because he's been doing this for years & years with the exact same line, I'm sure it's just reflex to him now. So if he says it, whatever. I'm not going to call him out on it anymore. If it makes him hesitate "oh Suds doesn't like it when I do that. Maybe I shouldn't. Or maybe I should." Truth be told I don't really care. I'm just going to play my game. He should just know if you dish it out, you have to be able to take it when it's your turn.
There was a side topic in here about someone with an illegal serve and if one should say something. This notion about speaking up as a sign you're off your game I completely disagree with. Not that long ago Timo Boll spoke up vs someone who had an illegal serve and sure enough a few plays later the umpire called it. Was Timo being weak minded there? No. The person was breaking the rule and rather than dealing with the disadvantage of not being able to see the serve the rest of the match, he rectified the situation to give himself the best possible chance of winning. Saying something doesn't necessarily mean one is tilted.