Vertigo you look at these things a lot closer than I do, I never even noticed that.
Make sure you have a copy/backup of this skin before you play with it, always a good idea, plus I'm not sure you can get this one anymore.
Skinstudio
Edit Start Menu
When that window pops up, click on "Code Editor" tab on the bottom towards the right
"StartPanel.UserPane" should be showing in the dropdown box kind of in the middle... click on the dropdown arrow to the right of that. When the list pops up, scroll up about 22 items and click on "StartMenu.Animation1". You should see this in the box below:
AnimTimerRate=1
Image=halloween\skeletonjump.nwa
Trans=1
PerPixel=1
Alignment=1
FrameCount=128
MouseOverStopFrame=127
MouseOverStartFrame=56
Vert=1
Change Alignment=1 to Alignment=2
Apply, save etc.
That should do it for you, does me. It also shifts the skeleton to the right a tad, but I don't think you'll mind that, seems fine.