It could be because the domains in question violate their terms in some way and they found out. Or, it could simply be an oversight.
Sedo actually closed my whole account about a month back by accident and I had the same message for all of my parked domains (big mess). I have since been reinstated, but I know exactly what message you are talking about.
I'd drop them a note via their new support portal. They are usually pretty quick to answer.
Good luck.
Sully