Hmm, never seen that before. If you can then wait until the next build and see if that fixes it, shouldn't take long until then.
This is an issue with how AOSP handles fingerprint. I've been searching for a way to fix that, but haven't found one yet.
Shouldn't be too much of an issue if it only happened once. Might wanna try out different dialer/contacts apps though, for example Google's.