Tesla extended gains in premarket trading Tuesday following Monday’s big jump in the shares, but investors may soon begin thinking about how well the company’s cars drive themselves following Sunday’s successful robo-taxi service launch.

The NHTSA contacted Tesla after several videos showed incidents involving its robotaxis after the service was launched in Austin on Sunday.

Tesla’s stock shot higher after Sunday’s launch of the EV maker’s eagerly anticipated — and recently delayed — robotaxi service in Austin, Texas.