The cough is one of the last things to linger when you've been ill, and it's not that out of the ordinary to have some fading and return of some of the lingering symptoms with some infections. I've been seeing a lot of that this year with friends and people I work with. If you have asthma, it's probably worse. I definitely think my asthma contributes to my lingering coughs when I get sick, and I become more susceptible to breathing difficulties that are temperature related.
The best you can probably do is make sure you're drinking plenty of fluids, to keep your throat irrigated, and keep some over the counter cough medicine handy just in case. Also, if you have asthma, make sure to keep as warm as you can. Sometimes cold air can aggravate the symptoms as well.