Cough - am I paranoid?

[Ladybird L]

I went for a longish ride today (2hrs). My mare (she has asthma) seemed totally fine, we cantered, jumped and trotted and and she was in no bother at all. Once we had walked back to the yard (7mins, hilly) her breathing was 16 breaths per minute.
I halted in the middle of the yard when she did one short cough. I’m worried?! Is it the asthma? Or could it just be a normal nosefull of dust? Am I paranoid??

 

[Equi]

I don’t think I would worry too much about one cough. If it’s a regular thing I’d consult a vet.