Yes, but I treat them exactly as I would anyone else.

I sold Steve Carell a phone when I worked at Apple. I treated him as I would any customer until I was doing the final keystrokes. I asked

"“Is your last name spelled with one R or two?”

He laughed. I saw him a few other times; we just nodded heads.

I've also saw Steve Tyler there several times,. I took a picture of his dogs, not him. :)

I walked by Liza Minelli in Boston many years ago. I just nodded in recognition and kept walking.