Maybe you also changed other habits you can think of, apart from the wheat stop? Healthier lifestyle in general? More sports? Or maybe it's not because you stopped wheat, but you started with a replacement?
In my case, it was a controlled experiment. I was suspicious that it might NOT have been wheat so I let it run for this year too and so far so good with pollen season almost over. Of course, the real test would be to consume large amounts of wheat this year, wait til next spring and see if the allergies return.