"Well, of course there are missing details. This is Star Tribune story."
You're right, however:
"They probably didn't object to a search."
Most people think a request to search is not a mere request, but an order. The police are wearing uniforms & are armed. The legal phrase is, "operating under color of law."
Some people believe that a refusal to permit a search is in itself, "reasonable suspicion."
Most of the "people" that believe this are cops.
It turns out that the khat was in shopping bags, in plain sight, in the back seat of the vehicle.
And, yes, local LEO's have plenty of experience with khat to know it when they see it.