Truck Stop

The AP via BizBlog Daily.

Explosives scare stops traffic on I-65

Authorities briefly closed Interstate 65 Tuesday after a police dog indicated explosives were on board a truck that had been stopped for an improper tag, but a search turned up nothing...
FBI spokesman Jeff Fuqua said federal law enforcement learned of a tractor-trailer rig traveling with an "obviously altered tag" and notified police.

emphasis mine

What's up with this? Sounds kinda fishy to me? Who travels around with an "obviously altered tag"? And how did the FBI get involved before the stop?