Sense Sonnet - Tickler

Been Warned

A sign is posted on the door,
"Beware of Dog! Danger inside!"
A guy enters the country store,
Sees the dog and is mystified.
Middle of the floor, sound asleep,
Lying there a harmless old hound,
Not moving, not making a peep.
This is the only dog around.
What is the danger to beware?
The stranger asks the owner why
The door has a sign posted there.
The owner says this in reply,

"The sign's posted as a prelim"
"So you will not trip over him."