Autopilot features are demonstrated in a Tesla Model S during a Tesla event in Palo Alto, California October 14, 2015.
CNN  — 

Federal regulators want to know what Elon Musk meant in a Tweet about disabling driver alerts on Tesla’s “Full Self Driving” driver assist system.

The National Highway Traffic Safety Administration confirmed Monday that it is in contact with Tesla about Musk’s tweet in which he “agreed” that Tesla drivers should be allowed to disable the alert reminding them to keep their hands on the steering wheel while in “Full Self Driving” mode, which is a driver assist system in an early “beta” version that does not fully drive the car itself.

On December 31, Musk replied to a tweet by @WholeMarsBlog that said “users with more than 10,000 miles on FSD Beta should be given the option to turn off the steering wheel nag.”

“Agreed, update coming in Jan,” Musk replied.

NHTSA says the issue falls under the agency’s existing investigation into the performance of Tesla’s driver assist systems.

“The investigation opening was motivated by an accumulation of crashes in which Tesla vehicles, operating with Autopilot engaged, struck stationary in-road or roadside first responder vehicles tending to pre-existing collision scenes,” reads the summary of the investigation which opened in June.

The federal inquiry into the tweet was first reported by the Associated Press.