I haven't had any problems. I was re-certified by the NBU for DASH last year. I make sure all my documentation is in order and properly filed (any imports come through TRACES and I send copies of all the health certificates to APHA).
The only odd thing I saw recently, which was a bit of bureaucracy really, was when I received the report on my DASH recertification was that they asked me to keep a record of all my negative disease checks. Its stupid really because disease monitoring is part of what I do at every inspection. By definition, if I note none on the record card, that's a negative result. As I've said before, I use a German program called "Zucht Buch" for all my stock records so I can easily answer any question they may have. Of course, it's all transferred to BeeBreed at the end of the year too.