What happened

Shares of electric truck start-up Rivian Automotive (RIVN 5.35%) slid in early trading Tuesday before turning around in the late morning and going green in the afternoon, following a rising Nasdaq higher.

As of 1:55 p.m. ET, shares of Rivian stock were up by a solid 3% -- but investors shouldn't let that fact make them complacent.

Rivian R1T pickup truck in the snow.

Image source: Rivian.

So what

Turns out, there's some disturbing news about Rivian afoot, and while it's not getting a whole lot of press yet, it does bear watching. Over the weekend, a Rivian vehicle caught fire at the company's production plant in Normal, Illinois. As the Normal Fire Department explained in a press release:  "Normal Firefighters were called to the Rivian Automotive Plant at 100 N. Rivian Motorway just after 9 p.m. for the report of a vehicle on fire inside the building." Upon arrival, firefighters found an unspecified Rivian EV (whether an R1T, an R1S, or one of the new electric delivery vans it's building for Amazon was not made clear) "on fire on a vehicle lift." Between the spray from the building's sprinkler system and the efforts of the firefighters, the blaze was extinguished without further incident.

However, "the cause of the fire is [still] under investigation," and no conclusions have yet been drawn.

Now what

Reporting on this story Monday, InsideEVs.com noted that "the recent fire wasn't the first of its kind at the Rivian factory. Back in October, a small battery fire broke out in an automated battery sub-assembly area." 

Now granted, a pair fires does not a pattern make. One cannot say at this point that there is definitely something wrong with Rivian's vehicles, or with their design, or with the batteries used to power them. That being said, a pair of fires does at least warrant questioning whether something might be up with Rivian's design. Anyone investing in the stock should at this point start getting alert to the potential that there is a design problem. If there is, Rivian's stock price could be at risk.

Forewarned is forearmed.