Phone passcode

I came home last weekend (im in the Army so only get home at weekends) to find my GF put a passcode on her phone. The last time we had drunk sex i told her about my fantasy of her sleeping with other guys behind my back/flirting with other guys whilst shes out. Do you think shes met someone or is this just a coincidence?
 
She could be trying to just go with it a little and get the gears rolling in your head to turn you on. She probably hasn't talked to anyone and just wants to turn you on and make you wonder.