Legal or illegal?

So my friend got pulled over for speeding, the cop took her license and everything wrote her a ticket, but asked her to step out of the car to sign paperwork (???weird) and said drive safe and gave her license back. As soon as she sat back in her car the cop came back and asked “when was the last time marijuana was smoked this car” and told her to step out and got his K-9 and searched the car, found a small bit, and charged her with possession. Jw if it’s legal since she was already let go and about to drive off. This is in VA btw since the laws differ from state to state.