I dont know anything about your machine but it could possible be that it is running an OEM Version of Mach and as such has some specially configured setup. However looking at their site they seem to just have the standard Mach available for download so it doesnt seem to be the case.
It is likely that they are doing this for support reasons, so if you did upgrade and needed help then they would not support you with the newer revision.
You could if you wished save your xml and any custom macros, brains and screensets/bitmaps you use and then install the newer version, if you have problems then you can go back to the older version and just paste in the saved files.
Hood