It does seem rather peculiar. I don't recall any previous reports of such behaviour and it seems to be working as expected for me.
When a file is saved there doesn't seem to be any reason why PE6 would set the timestamp. Windows would be told to open or create the file, the data would be written to it and that's the end of it. Windows itself would provide the timestamp rather than PE6.
Could it be you are looking at a file other than the one you are actually saving, an earlier or backup copy ?
If you repeatedly save the file, does it stay fixed or does the timestamp update but always lag by the same amount. You may need to wait at least a minute between saves for a file timestamp to appear differently to what it had been in Explorer.
Pressing F5 or clicking View->Refresh should update the Explorer window should it be showing older, cached, information.
Added: You can also open your Word file, change the text and save that, check if its timestamp changes.
It might be worth checking View->Choose Details in Explorer to ensure it is showing Date Modified, not Date Created.