Could be - it would be worth going to your doctor to see if they can do an allergy test on you. I am terribly, desperately allergic to cats, and always have been. They bring on asthma, sneezing, wheezing, swollen eyes, hives etc etc....
I was determined growing up that I would always have cats, no matter what, and I started taking precautions around the house - ie, no carpets or curtains, special asthma mattress covers etc...which really help.
But in the end I have become immune to cats....believe it or not. It can and does happen, and I have been exposing myself to cats since an early age despite the allergic reaction - now I can stick my face right into any cats fur, take a big sniff, and not have anything happen at all!!
This can be medically induced, too, but it takes a couple of years.