Is it just me or does she have no sense of humor?

So yesterday I was joking around with my mom about how the leader/celebrity of our religious community was messing around on his iPhone while the priest that hung around with him was answering all the questions and telling us things about God.

What I said was "What if he was like 'Yes I finally got past this level' and started getting excited because gaming the whole time? And then what if he high fived a kid there who said he played the same game?"

But my mom said "That is such a childish and immature thing to say." Truth is that I'm 19 and that the leader of religious community said that he is was on the phone the whole time because he got lots of emails from people and he had to keep in touch.

But is it really immature or does she have no sense of humor?

Added (1). I don't think it had anything to do with respect, I could have made a joke about someone who wasn't a religious leader and she would have said the same thing.

There's difference between respecting someone in a higher position & humor.