Maybe the dog was feeling 'scent-imental'

You should've screamed "it's a bomb".

How did your dog get back home?

they don't bark they sit

They're usually trained to sit when they detect something, not bark.

Doge: Something is suspicious. This man smells like a bitch.

You should've sniffed his shirt and said smells like the same old ****** I left home with

Different dogs are trained to alert differently. There isn't any set "alert" for drug dogs. It could be an ear twitch, or barking, or sitting, etc. so this could be how that dog alerted to the presence of drugs.

Ok so I help train these dogs here in Texas. They are trained to sit or follow the scent of explosives, and to ignore everything else (food, other pet scents, people talking, etc.) Sometimes dogs will be dogs and they get a little goofy, but it's up to the handler to discern what's curious sniffing and what's a serious change in behavior.

That sucks but I'm glad the security is good - better safe than sorry