Why she did this?

This afternoon at school after lunch we were back in class n when i arrived at my place i saw that my pencil case wasn't on my desk (i leave it on the desk b4 lunch) so i went to my locker thinking that i may have forgetting it here n when i go back in class the pencil case was on my desk... this girl hid it for making me a joke lol.. but why she did this, is it flirting, this girl has been teasing me a few times previously too