Things seem to have been going well for Tesla recently. When the company revealed its Model 3 a few month ago, there were nearly 300,000 reservations for the compact sedan in just three days; and yesterday brought news that Tesla Model S batteries weren’t losing much capacity with age.

But now, Tesla is facing some bad news in the form of allegations that it urged customers to sign confidentiality agreements over mechanical issues with the Model S.

Bryan Thomas, a representative from the US National Highway Traffic Safety Administration (NHTSA), told Reuters that the agency is "examining the potential suspension issue on the Tesla Model S, and is seeking additional information from vehicle owners and the company."

The NHTSA said it learned that Tesla had entered into a “troublesome nondisclosure agreement” with a Model S owner who had mechanical problems with his vehicle.

Right now, the NHTSA isn’t investigating Tesla; it’s just in “data collection mode.” Elon Musk’s company confirmed this in a blog post. "[The] NHTSA has not opened any investigation nor has it even started a 'preliminary evaluation,' which is the lowest form of formal investigatory work that it does."

But NHTSA Administrator Mark Rosekind said: "Part of what we have to figure out is whether or not (non-disclosure agreements) might have impeded people making (complaints).” He added that it was unclear how many other Tesla customers, if any, had signed similar agreements.

Automotive site Daily Kanban reported the story of the driver who took his 2013 Model S, which had 73,000 miles on it, in for a service after the left front hub assembly separated from the upper control arm. Technicians said it showed an unusually high amount of wear caused by a loose, rusty ball joint.

The Model S was out of warranty, but, as the broken suspension was caused by a defective part, it was sent to Tesla management to find out if they would replace it for free.

It was agreed that the company would pay 50 percent of the $3100 repair bill as long as the customer signed a “Goodwill agreement” that ensured he wouldn’t discuss terms of the deal. It also stated that Tesla wouldn’t be responsible for "any and all claims or damages arising out of or in any way connected with any claims or incidents leading or related to our provision of Goodwill [paying half of the repair cost]."

Tesla says that the Daily Kanban "fabricated this issue, then caused negative and incorrect news to be written about Tesla by reputable institutions.” It added that it regularly meets with the NHTSA on a voluntary basis to discuss safety matters.

But the transport agency doesn’t seem convinced that Tesla has done nothing wrong. "The agency immediately informed Tesla that any language implying that consumers should not contact the agency regarding safety concerns is unacceptable, and NHTSA expects Tesla to eliminate any such language."

Tesla said that the idea that it would ask a customer to sign a document preventing them from talking to the NHTSA or any other government agency was "preposterous."

"This agreement never even comes close to mentioning NHTSA or the government and it has nothing to do with trying to stop someone from communicating with NHTSA or the government about our cars. We have absolutely no desire to do something like that," the company said.

As noted by Forbes, a Model X owner recently reported to the Better Business Bureau that Tesla canceled her registration and repossessed her new SUV when she pointed out the multiple defects in the vehicle, and then refused to refund her money unless she signed an NDA. Breaking the agreement would have landed her with a $150,000 penalty violation fine.