I would take an opportune moment when we were alone and give her a hug and tell her how much it meant to you that she shared the quilt with her friends. That you are so happy that she is your MIL because she raised such a wonderful son and (insert several things here) . I'm sure you can find a few things about her to really seriously praise.
I then would tell her how glad you are that she is your MIL. You have acquaintances that relate horrible MIL incidents to you and that you are always so happy that she is not like that.
You get way farther with honey than with vinegar!! grin