Do you mean marks of exploration, or badges of exploration? If you only got 5 badges of exploration then that is a bug.
The marks of exploration are from doing the same thing basically (explore and complete 3 system missions in the B'Tran cluster) and can only be repeated every 20 hours.
Yeah, when it came up it had only ONE item, the Exploration badges...but it only gave me 5 of them. I've done lots of these in other areas so I know it should be more than 5...unless there's something wrong with it in the Borg area.