Ferret losing hair in the tail?

I have two male ferrets, they are both under 2 year of age. One of them I noticed is losing hair in his tail. I've read about ferret adrenal disease also tail alopecia which makes them lose hair in their tail sometimes during the summer. I can't find a lot of information on the tail alopecia, at least enough to satisfy me. Both ferrets are very active, not thin and showing no hair loss on any other part of the body. Is tail alopecia really common with ferret owners? Are there any other symptoms besides hair loss or should I rush him to the vet to have him checked for adrenal disease?