Good point, I'll watch for it. There's three cases like that, but there's another breakdown that didn't identify where the 3-box pack came from, that didn't have one of the big four or a Fleur. I call that a "Ginny" case below.
Not all of the Fleurs were found as a third item, so they might have picked a few of them to fill out the "one per case" rule and put the other half in with the others. Or maybe we're trying to see too much in random happenings and 2% of the print run!
The "clusters" are starting to take some more shape.
All five DE2 cases also held Dumbledore-Padma-Parvati-Ginny.
All three Dan cases also held Padma-Parvati-Ginny-Maxime.
DE1 split into two groups:
Three DE1 cases also held Dumbledore-Junior-Ginny-Maxime.
Three DE1 cases also held Fleur-Cho-Senior-Junior.
Three Fleur cases also held Cho-Parvati-Senior-Maxime.
(One of these offered an extra DE1, 6 autos total)
The two oddballs have a relationship, too:
Fleur -Cho-Padma-Senior-Junior
Ginny-Cho-Padma-Senior-Junior
The Quad case reported Padma-Senior before the reporter found the Quad and quit opening boxes after five, so perhaps the 'oddballs' were in a packaging cluster for the Quad cards and didn't get lucky.
Not all of the case breakdowns reported the autos box-by-box, but the ones that reported it fit Tom's "lead character" theory. Possibly the three-insert-box groupings were, if you shoot for either 750 boxes or the 900 total-made target:
125-150 Chance-for-a-Quad
125-150 Daniel Radcliffe
125-150 DE1-A
125-150 DE1-B
125-150 DE2
125-150 Fleur (also found in DE1-B)
That would put every signer into three groups (375-450) except for Dumbledore and Fleur in two groups (250-300) and Dan in just one (125-150). That makes sense, so it's probably completely wrong.

It could be we're seeing a pattern in one part of the manufacturing process and there might have been different patterns early or late, but it does explain why we see fewer Dumbledores and more DE1 than DE2.