[axlt2002]

don't know why, but apparently it takes a bit of time for kodi to retrieve this info.
adding a bit of sleep should give a proper result.

Code:

xbmc.getInfoLabel('System.OSVersionInfo')
xbmc.sleep(100)
label = xbmc.getInfoLabel('System.OSVersionInfo')
xbmc.log( "[%s] - %s" % ( addonName, label ) )

That solved the issue! Thanks a lot!