Who knows, he is still young. Sometimes young people change for the better... maybe he realized he acted silly for most of his life right until now...
He used to be such a PITA.... or is he feeling really, really, really sorry for us.
Boys & men often give each other a lot of grief as a way to say “I love you”. Whilst the relationship between brothers will always be different than the relationship you share with them, it’s also possible that he’s clued into the fact that giving his brother a hard time
A) Is also giving YOU a hard time (oops)
B) May not always be appropriate in a family setting anymore... where there are wives and children present, instead of just “the boys”.
Aka, instead of feeling sorry for you? Or fundamentally changing.? He may just be growing up.
Which means I would expect him to still be a jerk to your husband, his brother, on a fairly regular basis. Just not in
every situation he is in with his brother anymore.
When men in a family wake up one day & realize that they’re not “the kids” anymore? But role models, and figures of authority? The adults in a family? (Takes most men years past the kids being born, we love them dearly, but in some things they’re not quite bright.) They tend to shift into mischievous joking around when the nieces and nephews and wives are around, and save the hardcore stuff for after bedtime, or when they think they’re alone, or in greeting/leaving.
I’m generalizing, for sure. This is my experience and observation of young men becoming Men. They retain who they are. They simply modify when, where, and how much of certain behaviors they show.