Sara, I think such encounters are difficult for both the cross dresser and the SA. I've read many threads and postings of positive encounters with sales associates. Even if the laws of the state or municipality are favorable to cross dressers, it is still a balancing act for the SA to deal with the cross dresser and other shoppers, presumably women. I can only imagine a large retail chain has a printed manual explaining the legalities of operating a store for the manager and employees to read and consult. In my state cross dressers are protected by law. I believe you did the absolute correct thing in diffusing any potential situation. Your avatar picture is super feminine (your super cute, too)! It gave the SA relief because the shopping experience you were having is not all that common for a young SA. Over the years I have shopped at specialty stores and sensed a uneasiness with SA. Why? I guess because it is not a common experience for them.
If you are a lone SA or two operating a store, you really do not know what you will experience each day. Without being considered crude, as an example, I accompanied my wife to JCPenny. While she was perusing the nylon nightgowns, she came across one that had been 'soiled' by an obvious male pervert who decided to 'jack off' in the store. Disgusting!
Any SA in any small store has to do an evaluation on the spot of any customer walking through the door.
