Did you hear that?

When I was in college there were times that I would say something to a friend and then get frustrated that they ignored me and didn't answer. When in actuality, I had said it in my head, not out loud. There were even times when someone wouldn't respond that I would ask someone else near me if they heard me say something, just to make sure I had said it out loud and not in my head.
Today I had one of those flashbacks, where I am positive I spoke out loud. That I said "Good morning Ms. (according to HIPAA I can't reveal this persons identity). How are you doing this morning?". And I am met with silence...nothing. So I try again..."How is your day going so far? Ms. (you fill in the blank)." Again nothing...a stony silence. And what makes it worse is that there was no one else around for me to ask if they heard me. What if I have reverted back to thinking I have said something and actually its all in my head?
This could ruin me as a teacher...thinking I have taught lessons and the students never heard a word of my amazing lesson going on in my head.

This is not good, not good at all.