Some recalls can happen after the government receives reports of a problem, investigates that problem and determines a recall is necessary. To that end, the National Highway Traffic Safety Administration is currently investigating a potential problem in certain Mazda vehicles.
NHTSA has opened an investigation into the 2010-2013 Mazda CX-9. It's unclear how many vehicles are potentially affected, because the vehicle population is listed as "confidential" in the Office of Defects Investigation document explaining the investigation.
The side curtain airbags lie at the heart of the matter. According to two complaints and other field reports, both side curtain airbags deployed inadvertently and simultaneously without a crash being involved. One of the complaints alleges that injuries stemmed from the improper airbag deployment.
NHTSA will continue to investigate the issue and, if deemed necessary, compel Mazda to issue a recall for every vehicle potentially affected by this alleged defect. If it just happens to be a freak occurrence, the investigation can end without a recall. Mazda can issue a voluntary recall on its own, as well.