I think tipping in general has gotten a bit crazy. Today my wife and I ate in a cafeteria. We purchased our food including beverage and carried our trays to a vacant table. While we were eating, a lady came by and gave us her card and said "Hi, I am soandso, and I"ll be your server." She hadn't done anything for us except smile and expected a tip. I hope she wasn't too disappointed.
I even see tip jars at checkout and cashiers. Does someone expect a tip for taking my money? Most of them couldn't even make change if the computer didn't do it for them. I think this must be some weird trend that started in California.
I always tip well for good service, and I have always experienced excellent service while cruising.