Right, this was clarified by Romney campaign immediately afterward, as reported in WashPost:
“The NRA did not endorse in the 2002 campaign,” said spokesman Kevin Madden, when asked about Romney’s comments. “Mitt Romney as a candidate received a respectable B grade rating from the NRA, and when he was governor he had the support of the NRA and the Gun Owners Action League in relaxing some of the state’s burdensome licensing regulations.”
Clarified? What a careful euphemism for reversal.