It is not always how someone says something but how you react as well. His comment was not "older than I thought. wow" ...old people suck. Or anything necessarily bad. What is his comment you don't like on an internet forum going to do to you? Don't worry about it so much.

Also yes he can be less rude to you.

The fact that I am more addressing you and not marc does not mean I think he is 100% not rude and so you are wrong but that the whole issue can be moot if you don't worry about it then if he continues it shows more about him than you if only one person is partaking in such a thing.