That's... Yeah. Pretty ridiculous. A week? Should be several months to count as necroposting. What if you weren't paying attention to the dates? I haven't been on my account recently, so I wasn't able to respond.
The general interpretation of moderators (warpy, ithilion, me) on necroposting of past 3 months has been more flex anyway. The rule mentions a month, but we consider a post that actually adds to the value of a discussion on a (potentially) meaningful suggestion not even a necropost. People contaminating a thread by shouting 'necropost' (by mini modding) actually do more off-topic damage to a thread. And why kill the possibility to add useful feedback on approved and/or highly appreciated suggestion threads anyway? Therefore, we feel reluctant to call necroposts ... and closing a thread only because someone was (allegedly) necroposting is something I would not advise to do either.