Hi
Hope I may be able to offer you some help. I have had serve asthma since childhood. I have a nebuliser at home, so I have been through most problems at some times.
Are you coughing at night? This is often a sign of asthma detiorating.
Do you check your peak flow. some people do some people don't again you can pick up signs of a deterioration if your peak flow is dropping.
I assume that you are not suffering or getting over a cold or flu however mild, as there is a chance that that might have been causing some congestion making things worse.
You sound very fit, but remember that we are going through a change in season at the moment in england. I don't know where you are but when the weather suddenly changes from spring to summer, ect. It is the highest addmition rates of astham into A and E.
I expect that this is just a temporary blip but if it was to continue over the weekend I would get to see your GP on monday. Also remember that if you use your blue inhaler and your symptons get worse or don't improve get your self to A and E. Believe me they would much rather treat some one suffer a mild attack than some one who ends up in Intensive Care. Also if a any point you find it increasing hard to breath call an ambulance that way you can get treatment on the way to hospital. That is what the service is for. I have been told off numerous times because I have driven myself rather than calling an ambulance.
Don't mean to worry you just to make sure you had the facts. I am sure this is just a temp glich. But keep an eye over the weekend and if things have not improved got to your gp.
Hope you feel better soon