Ever Embarrass Someone Unintentionally and Realize You Were Correct?

Ran into couple women I have know over the years not close friends but acquaintances that you knew their family and they knew yours. The were in the grocery store and I saw them talking one waved and said hi so I walked over to say hi to both of them. I knew that the ones daughter had married the others ones son. So I said what are the 2 mother in laws plotting? One said what would we be plotting, I said probably wondering when you were going to become grandmas!! Both their faces turned red and they were speechless finally the one admitted they were, I said well dont let me stop you have a good day.