Never, No flair ups on cycle at all, at least that I would relate to that. It can be brough on by things like intense cardio, but just because I did that on a cutting cycle, I wont lay the blame there. My estrogen levels are actually much lower on cycle due to the attention I give them to keep them that way. The first time I tried Letro, I got them too low in fact.
I dont think the connection is that simple, I think that it must be some long term effects.
Also, now that I am older, my asthma has pretty much been gotten under control. It is no where near as bad as it used to be and I am controlling it without daily maintenance drugs.