Well, not really a gift and not really a comp.
Last night we went to a big, fancy steakhouse to celebrate my BF's completion of his masters. We were comped a dessert and a cocktail to celebrate. Very nice and I know to tip on the comped items.
However, during the meal, we were informed by our server that the the gentleman at the next table offered to buy the wine for our meal. VERY nice, no? We'd already ordered, so he may not have know what he was getting into (of course, he may have found our from the server before his offer.). Important to note that the server waiting on his table was not the server waiting on our table.
We extended our gracious thanks to him and he came over to chat with us for a few moments.
So, the question is...should I tip on the wine that was gifted to us? It's not comped, the other customer paid for it and assumingly tipped his server on his bill. But our server was the one who took our order and served us. I did tip on it, of course, but did I follow protocol?