When I worked in the food business my cousin was waiting tables two days before christmas and wrote "happy holidays" on the back of their bill. They flipped out on her, they don't celebrate holidays. I thought they were just being mean. Why not just say thanks. All it means is you wish them well and you took the time to say so. Some people are way to sensitive about this season. I would never be offended if someone said "happy kwanza" (I think I spelled it wrong) or anything that was not the usual for me. I would find that endearing and say thank you. I guess it all comes down to their true inner beauty and kindness. So I say from my life to yours, "Merry Christmas."