this is a good opportunity

You should try to let your "small boss" passing some words to "big boss".

You might want to say a lot of good things about your big boss. He is smart, strong leadership, being expert in XXX, and you admire him a lot, etc, etc.. and you feel sorry to say something you did not mean it, etc. etc. And ask a favor from your small boss to repair the relationship with big boss. - anyway, take the chance. It also makes small boss looking good in front of big boss, so she will be happy to do it.