A Night to Remember

You immediately bring up what had just happened to the guy, named Mark, Katie has just been talking to.
"Mark has just dropped behind you!" you shout.
"Calm down, there is no need to yell," Katie explains.
"But I--," you start.
"Don't worry about it," Katie assures you.

Katie denies that she did anything and quickly changes the topic. You are still suspicious about what happened as Katie walks into the kitchen to get another drink. You suddenly realize Katie has left her purse behind. Do you look through her purse to figure out what is happening or just leave the situation alone hoping that your friend would never lie to you?