Since these are Skin files and not WB's files I believe it would not fall under a WB false positive. but it still could be a false positive..
It suprises me that all of a sudden it finds a 4 year old file suspicious, as I doubt you installed the skin any time recently since its no longer available here for download. So IMO i think it would be a false positive, but if you dont want to take the chance you can always remove it.
I was going to download and investigate it but alas as I stated earlier is not available for download..