My new MIL is phony

My husband was a typical mommy boy before we got married and he has has quit jumping at her every demand since we been married and still occasionally run her errands of do whatever she needs around the house despite her being married. However, my husband works out of town majority of the time and with us having a newborn I sometimes take him over to see the baby. One thing that I have noticed is that when my husband is not around she shows another side. She’s not as friendly or if one of her daughters are around it seems like she’ll be passive aggressive or say something that she wouldn’t say if it was just us around. Like she needs an audience to be that way.

I am treading lightly and I am on the verge of saying something to my husband the next time I observe this but wondering if I should say anything since I am a newlywed and don’t want to start off with issues with my mil early on.