What happened

General Motors (GM 0.70%) didn't exactly cruise smoothly into the weekend. On the back of concerns about its Cruise self-driving program, the automaker's shares fell by nearly 4% on Friday, well eclipsing the 1% or so drop of the S&P 500 index.

So what

The blowback was understandable, as it came on the back of news that the National Highway Traffic Safety Administration (NHTSA) has launched an investigation into Cruise. The probe stemmed from complaints the agency has received about cars in the program braking abruptly and, more worryingly, becoming immobilized in the middle of trips. 

While those two types of incidents seem to be isolated from each other in General Motors' case, the NHTSA said in a filing that "This may introduce multiple potential hazards such as a collision with a Cruise vehicle, risk to a stranded passenger exiting an immobilized Cruise vehicle, or obstruction of other traffic including emergency vehicles."

Drew Pusateri, a spokesman for Cruise, told CNBC that the self-driving unit would "fully cooperate" with the agency's probe. He took pains to point out that Cruise's experimental vehicles have self-driven nearly 700,000 real-world miles in total so far. And they've been put through their paces in what he described as an "extremely complex urban environment."

Now what

Cruise is the great shining hope of General Motors in the autonomous sphere -- and it nearly goes without saying that autonomous vehicles are a goal almost the entire auto industry is striving toward. It doesn't do the company any good to have negative press about its efforts. Hopefully for it and its shareholders, these incidents are rare, truly isolated, and will prove eminently fixable.