Having been in the business for 12 years now, my understanding of hobby etiquette, especially when it comes to situations like this is either hobbyist or companion must ALWAYS practice respect of privacy, and use the utmost discretion. ALWAYS. There's boundaries that shouldn't be crossed. I'm sure there are those rare instances where BOTH parties agree on what is OK and and what is NOT OK to do if one happens to see the other in public. If both adults agree on giving a smile or a brief "Hi", that's up to them.
FYI, I am old school. I practice hobby etiquette, discretion, and privacy towards anyone in the hobby. I would hope I get the same respect back.
It's all a matter of respect which I am sure everyone would appreciate.
MarieLynn