I've yet to see the first runner team that would NOT look like 'probable cause for further examination'.
Single runners, sure. But in a whole team? Odds are low.
That said, I think the cops should be least of your (runners) worries.
Mafia/Yakuza/Koshari/Triad/<inser syndicate> should always be larger concerns. They stand to gain much more from intercepting said traffic: competitor loses stuff to sell, they get free stuff to sell, that's double profit!
Not to mention gangs looking for a way to make an extra buck, or just a way to get a free high.
Also, if you're looking for reasons why cops or mobsters would come after the innocent-looking smugglers, maybe they have an informer who gave 'em a time and a place. Or a description of the package. Or a description of one of the runners. That'd be more enough to start trouble.
In fact, the employer having a mole seems very likely. Why else would they be hiring a runner team to do a smugglers work?
Edit/add: Which can create a funny situation. Instead of mobsters or cops, maybe a group of smugglers will come after them. "We represent the Smugglers Union. This is our border, chummers. You tell your employers that if they want stuff to come across this border, they pay us, not you. You get that? Now hand over the merchandise. We'll deliver it when we get paid."