She have read what you said and this is exactly how she feel when it happen. So it can be adrenaline...do you know if it can be dangerous or something bad for the body ? Does this mean it can be a problem with the thing who release adrenaline in the body ?
Dude it's fine, tell her to not worry about it. Happens to me every once in a while, and has happened since I started smoking. If she thinks it's that annoying, tell her to smoke less next time. Or smoke more often so she has more of a tolerance/is used to it.