I agree wherearetheteaspoons - it was a definite let down after the triumph of 5.3 - really hoping that the rest of this week is not like that!
Welcome nmg85! I am also asthmatic, and would say two things - firstly, I found my breathing and tightness settled down a lot after about week 3 once I'd started developing a bit more familiarity with running, so do try and stick with it as long as it's just that sort of thing. Of course if you experience any symptoms of an actual asthma attack, don't keep going! I ran with my inhaler in a jacket pocket for a while to be extra careful too, and found that oddly reassuring when I was starting out, although I don't take one now.
Secondly, having very regular, organised breathing also helped a lot - one of the books I read when I was starting pointed out (on an unrelated note) that breathing in always on the same foot can lead to injury as you adjust your form ever so slightly when you breathe, so the author recommended sticking to a 3-2 pattern - breathe in for 3 steps, then breathe out quicker for 2. I decided to try this for those reasons, but also found that once I was able to settle into the pattern it became fairly automatic, and that ended up coincidentally being enormously helpful for any asthmatic feelings, as really it's panting/breathing too hard which was causing me problems, whereas having consistent, regular breathing all the way through the run was fine. It also gives you something to think about on the early runs which isn't 'I hate this, argh argh!' I hope that helps a little.