It's not like some kind of allergy in that once you get it you always get it. It just happens occasionally. Yeah, it sucks, but it only lasts 20-30 seconds or so. And knowing what's happening makes it not as alarming. If you had no idea there was such a thing and you started coughing, you'd freak.
There isn't anything that prevents it and nandi (a poster on another board) has posted clinical trials where the coughing occured with gear other than tren.
Bottom line, don't sweat it.