A passenger had asked for the wrap because he was cold, and was outraged when he was asked to pay $12 (£9.80).
Police said the man, 66, said he "would like to take someone behind the woodshed for this", which the pilot deemed threatening and then ordered the plane be diverted to Los Angeles.
No crime had been committed, police added.
The man had asked to speak to company representatives, arguing that he should not have to pay for the blanket because it was cold, the LA times reported.
He voluntarily left the flight when it landed in Los Angeles and caught another, Rob Pedregon, a spokesman for the Los Angeles airport police told AFP news agency.
"You know, if I was a passenger on board that plane I would have paid the $12 dollars for him," he added.