Why not? They are saying thank you... In a cult kind of way but still..

Gratitude is very good for a person spiritually. If you want to spiritually develop faster, have gratitude for all things. He's also not like an ordinary spirit. He's still Master and STILL can help us. He's actually came and helped me with something once since he's passed. He actually knew that I'd finally succeeded with something and his spirit showed up and helped me. I'd been dealing with something bad when he was still alive which he knew as he made a comment in class but I finally overcame it years after he'd passed. He must have been pleased with me for that as he showed up RIGHT AFTER I avoided the temptation which held me for so long and he did a healing on my head while he was in his spirit form. So he must be still out there watching over us and actually knows how we are doing.