<human>: This may be a bit long and/or confusing but here it goes...

I met my GF at University about a month and a half in to the school year, and we really like eachother and its getting pretty serious.  
But she has this thing where she gets enjoyment out of "teasing other guys", sometimes when I'm not even around.  
This doesnt seem to be a problem for her, but i always feel angry whenever she tells me about it (i only know thats it's happened 3 times, once she gave her female friend a hickey infront of another guy to "mess with him")
Yet I feel that I shouldnt be angry because she tells me its just for fun, but i'm more worried that other guys will get the wrong idea about her.  
We are also on Christmas break and live fairly far away from her so communication is mainly just texting so it would be tricky to bring it up with her.  
I just want to get feedback on whether I should just drop the whole thing and trust her or not...
If it helps, this is my first major relationship.  Please help

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: In serious relationship but GF likes to "tease" other guys, sometimes when I'm not around to intervene.  Feel extremely worried...