Missing at 17

Brandi Glanville's debut.

When Shannon is standing outside the convenience store, she bums a cigarette from a passerby and then meets Toby when she asks him for a light. They then go back to his place, where she spends the night. In the morning, she takes out a pack of cigarettes and is about to smoke one when Toby stops her.

If she had a pack of cigarettes already, why did she need to bum one from a stranger? If she didn't already have the pack, where did it come from? She never set foot in the store, so she couldn't have bought it there.