same thing happened for me, but at baltimore office. i was interviewed on 10/31 but after that, no more news. i guess local offices are all alike for pending cases, god knows when someone(if there's such a process and such a someone) will look at our cases again. ins service center might have a review process once in a while to resume the pending cases(like those RFEs) and they have every piece of information they need handy (i mean, unlike locals, which need to ask for another transfer or whatever from service center).
i called vsc today and the nice lady gave me the same 3-4 weeks wait message. thanks for letting us know how to push our cases, otherwise i guess our cases will be dusted on the shelf (if not recycle bin) forever.
another thing i'm in doubt is whether the cia check results may only go to the service center only (which makes sense to me because cia doesn't know where our cases are). at the time of our interview, the local officier may not know the result and can't approve it, then the vsc doesn't know local needs this info (unless they push this periodically), eventually it will become a deadlock until somebody finds out (of course, our 'blind' waiting time at expense). just my thoughts.
good luck to everyone!