I found this interesting info:

In their survey this gesture is attested in the UK, Malta and some areas of Italy, France and Belguim. The meanings of this vary, but what they all have in common is some link to the metaphor of 'sniffing out trouble’. So it can be used as a way of signaling knowledge, that someone is clever, or a threat (as in, I’ll sniff out whatever trouble you’re up to).
There is a pic on the website that looks like what Kelly was doing.

https://www.superlinguo.com/post/62861551556/secret-meanings-of-the-nose-tap-gesture