There are multiple border patrol checkpoints going through AZ, NM, TX and they often stop tour buses because they have a "tendency" to have drugs on board. They usually have their drug sniffing dogs with them and can claim the dogs caught a scent therefore giving the patrol reason to board the bus and do a search. Has happened to me on tour in TN, they didn't find anything on our bus but wasted a couple hours of our day off.
Anyone who has toured regularly should know this. Her tour manager really blew it not making sure all the drugs were off the bus/disposed of/consumed before they left California, but I guess there's only so much a TM can do.