I still feel bad

As a result of my literally bumping into the husband of my mom's old co-worker while taking the NBC Studios tour in LA, my mom and I got invited by him to go back stage of the Tonight Show with Johnny Carson, where he worked as a writer. We were carefully instructed about the house rules, including not looking at "Mr Carson" as he passed by, stay in this area, etc. They had a comedian warming up the crowd and I started to get bored and moseyed around a little bit. I made eye contact a couple of times with an older hippy dude... Chain smoking, eyes shifting nervously, pony tail, mumbling. Being 12 or so I didn't have any red flags go up, so when he looked at me again and nodded I said "Hello". He was actually very nice. He said he was going to be going out on stage as Johnny's guest, and he was really nervous because it's been a long time since he had been in front of a crowd. I asked if he used to be better and he said yes, but he was younger then, and it was much harder to please the younger generation. We paused as Ed McMahon announced Johnny and he did his monolgue, then talked a little more as they headed to commercial. Then he said he needed to take a few minutes to pump himself up, gather his courage, and again said he was really nervous and I should wish him luck. I did, and he shook my hand. I looked back and there was my mom, eyes wide open, with a look that I took as terror. Her jaw was shaking a bit, hand over her mouth, eyes like saucers. I suddenly got really nervous like I was just talking to Charles Manson or something. It occurred to me that I never even asked his name. As I walked away from him, my mom grabs me by the shoulders and said "Do you KNOW who that WAS!?! That was RINGO STARR!!!" Whie I knew the Beatles music and heard of John Lennon, I wasn't familiar with thier names, so I turned back to look at him and said, WAY too loudly: "Who's Ringo Starr?" Ringo turnd, looked at me, his shoulders slumped a bit, and he took a really, really long drag of his smoke before stepping it out. I will never forget the "what the fuck am I doing here?" look on his face for a brief moment before he plastered on a smile and got ready to be announced. I've always wished I had an opportunity to apologize for that. (he was there to announce and promote the first incarnation of his "All-Starr Band", once the crowd went nuts cheering for him you could see the nerves instantly melt away and he did great, but I still feel bad)