Amy was at the coffee shop Frothy Monkey in Nashville when she thought she saw a famous actor. However, it's more unusual to see famous actors rather than artists in Nashville so Amy didn't think it actually was the actor.
After some research it was indeed the actor Amy was thinking of Patrica Heaton. Heaton is in Nashville taping a new sitcom TV show. Amy was so stoked because she loves some of her work, however she didn't go up to Heaton and just thought it was cool she saw her. The guys attempted to guess who it was Amy saw in public, however none of them were able to guess correctly.
Fans would know Heaton the most from her time on the famous TV show Everybody Loves Raymond.