Do they have any pictures of their hives? I don't have any specific questions, cause I don't know what would be different! Every beekeeper, even living in the same area, seems to have different special ways of doing things they think are best. It's always really neat and fascinating to meet with them and compare notes. I've met more than one 80+ year old beekeeper who has commented "I still learn new things about beekeeping every day." !

And actually, I think its entirely possible it was your tanning oil! Especially if it happened to be banana or citris scented, because those scents smell particularly like pheromones that mean things to bees.