How I see it, you don't know that person on the phone, they have no idea who you are, and you'll probably never see or talk to that person again. So, the only person who knows your embarrassed is yourself. Shake it off and don't be too hard on yourself. Every thought is in passing, and the more you dwell on one, the more time it has to grow. Don't give those thoughts time to grow into embarrassment. You are the master of your mind.