We noticed this with latest version of Engintron nginx http caching proxy (as of June, 2017). That certificates which had expired do not appear to be renewed until we do a restart on Engintron or clear Engintron Cache.
I hope this would be of help to some people using caching and AutoSSL, perhaps adding an automatic script to prune caches every night will help resolve it.
I hope this would be of help to some people using caching and AutoSSL, perhaps adding an automatic script to prune caches every night will help resolve it.