Ok, so now that I have some attention span to comment with...
I saw Monday's comic, and I think the principal thing Marten was trying to do was cheer Padma up. It wasn't an attempt to dismiss her feelings or what she's trying to say so much as a "I'm really not sure what to say, so I'm going to focus on trying to make you feel better" deal. He went with self-deprecating humor because it was the safest target. More likely than not, he didn't even consider the possibility she would consider it dismissive. I think somewhere in the back of his mind, Marten thinks that if Padma has something to get off her chest, she'll just talk to him about it directly. It certainly wouldn't occur to him to think her comment was a sort of prelude or invitation to a serious discussion.
Of course, with today's comic, he is now worrying that something terrible may happen in his future. I think it's quite justified to prepare himself for the worst. After all, if you expect the end of the world tomorrow, and it does end, it's exactly what you expected. But if it doesn't end, then you will be pleasantly surprised!