Seeing a sudden influx of crashlytics error in an old version as soon as the new version is released

Last week we released an update to the app in the app store, version N.0. It was on a phased rollout. Several users reported a crash so the roll out was paused.

A fix to the crash was released to the app store this morning, version N.1 and the rollout resumed. However immediately following the release of N.1 to the app store there are lots of crash reports arriving in Crashlytics all of a sudden for version N.0.

Its as if N.0 has suddenly become available on the app store and everybody is downloading it, but that isn't the case, its definately N.1 displayed in the app store.

I don't understand why all these reports from a version of the app that is now no longer available has started arriving? Could be there some caching of versions in the app store or something and when N.1 release and the rollout resumed, the app store is actually automatically updateing people's phones with N.0 instead?

(There's a small number of non crash reports being reported in Crashlytics for N.1, proving its live and downloaded on some phones)