"The fact that GM took so long to report this defect says there was something very wrong with the company's values," he said.
GM said Friday that employees are now encouraged to discuss safety issues.
"We encourage employees to be factual in their statements and will continue to work with NHTSA to improve our safety processes," the company said in a statement.
But Clarence Ditlow, executive director of the nonprofit Center for Auto Safety, said what GM did isn't unusual. Automakers are required by federal law to report safety defects to the government within five days of discovering them, so they're careful not to use language that will trigger that law.
"The D-word — 'defect' — is banned in any auto company. GM just confirms it," Ditlow said.