We just sailed on Dec 28. When we were checking in at PC, The CM remarked, "Oh, it looks like someone just had a birthday." Our son turned 15 on Dec 11 - more than two weeks prior. The CM gave him a "I'm Celebration a Birthday" pin. He wore it and through out the day and CMs wished him happy birthday. Our server noticed it that night and said we would have a celebration on the last night. He asked if we were celebrating anything else. We said "no really" but did jokingly mentioned we celebrated our 20 year aniv in June and my daughter laughingly said she just completed her first semester in college.
Jump ahead to the last night... After deserts were ordered and delivered, the service team marched up and sang happy birthday, delivered the little round chocolate cake to my son, then started singing happy anniversary, gave us cakes and then gave our daughter a cake with sprinkles. She was given a "I'm Celebrating" pin too.