I took a quick look at the stuff which has been falling out of Colonies 15 and 16 today.
The removable tray under Colony 15 had lots of new wax platelets, indicating that they're busy building comb. There were also at least 3 Varroa bodies. This shouldn't be a surprise. Varroa are in all the colonies which I've encountered. This period after swarming has no brood so all the Varroa in the hive are clinging to the bees. Every mite which dies now does so before it can infest a brood cell, which is good news.