It does look like there may be something going on here. I see what he's talking about in Lantana, Light Mark, Polaris, Prowler, and Recoil. I didn't go through all my skins.
I deleted the .wb4 files, didn't help. Deleted my skin folders in Explorer, rebuilt the WBConfig list, reinstalled the skins fresh and deleted the .wb4 files, didn't help.
Personally it doesn't bother me that much, but it does seem to be there (for me too). I probably would have noticed it if it present prior to the Win10 1607 update. Here's my WB About if it might help:
Windows 10 Home (14393.rs1_release.160715-1616)
WindowBlinds 10 (015 - Windows 10 Edition) - 64 bit OS
Wblind.dll 2016/06/30 11:57:23
Wblind64.dll 2016/06/30 11:57:44
Wbsrv.dll 2016/03/04 08:54:32
WB10Config.exe 2016/06/30 15:47:45
Wbload.dll 2016/06/30 15:45:18
Screen.exe 2015/12/02 08:52:27
Using Intel HD4600 integrated graphics.
ESET Antivirus with WBCore.exe allowed in HIPS