Crescent symbol on Aes Grave of Tuder

On the Aes Grave semis of Tudur is a crescent symbol, described by CNG as a "retrograde C".

In Historia Numorum 1911, this is illustrated as a "hat" rather than a C or retrograde C, and seems to be considered a mark of value.

I wrote to David Perry, who is proposing computer symbols for Latin coinage, about this symbol — but he had never seen a crescent in the hat position. Does this particular orientation have a meaning in numismatics? Or was it a 19th century misreading of a crescent?

Some examples:
http://www.snible.org/coins/hn/umbria.html#22
http://www.coinarchives.com/a/lotviewer.php?LotID=139037&AucID=166&Lot=6025
http://www.coinarchives.com/a/lotviewer.php?LotID=131934&AucID=156&Lot=11
http://www.coinarchives.com/a/lotviewer.php?LotID=104468&AucID=111&Lot=1319

Perhaps an Aes Grave specialist is reading this post?