Neither did I.
The gesture was really more befitting a school girl than a first officer on a Starfleet vessel. Having said that, it made her strangely endearing. Never mind that she killed hundreds of Romulans in one sweep and not even loses one night's sleep over it. It's all part of her enigmatic charm.
I'm hazarding a guess that living for years with a sociopath renting space inside your own head might lead to some interesting personality shifts...