I have heard the same thing from everyone I know that has a current clearance and made a purchase - anywhere not just in MD... No clue why it happens, but it seems to be what is slowing down everyone with a clearance...
My understanding re: the delays for those that possess clearances- is there there is a block on gaining access (in an automated manner) to a cleared persons NICS information. As a result, the "reason for access" needs to be justified and manually provided. Again- it is my understanding this is to "help" protect any potential confidential information of those with a clearance.
Edit- Generally speaking- those in MD with clearances purchasing regulated items were never were exposed to this. This is because the MSP wasn't backed up and a 15 min further investigation (call) could be done in that 7 day window... Now, well, there wouldn't be this thread if there wasn't a problem.