I think all leaf mold really means is there's a mold specific to leaves and duff in the woods. Leaf mold is actually a really good thing for gardening. You'll find a lot in compost. In fact, if you just pile up fallen leaves and leave them to rot, your final result is a compost-like material generically called leaf mold.
I'm sure you can develop allergies to all kinds of things over time. I was never allergic to antibiotics, until I wound up in the ER from taking some. I also have some type of environmental or food allergy that I just ITCH constantly if I don't take a antihistamine every single day. Literally, I miss one dose and I'm itching like crazy. I would love to get allergy tested and find out what causes that, but you have to go without antihistamines for 5 days or so and I'd peel my skin clean off before I could manage that!
Quite possible. They're stirring up all kinds of dust and pollen and such when they do that.
