Vim detects a file on a VMS Samba share has changed when it has not

[BG - Ben Armstrong]

I am using Vim on Linux to edit files on a Samba share on VMS.  I am
finding that it detects a file has changed when it has not.  That is,
the following dialog box appears a couple of minutes after I start
editing:

W12: Warning: File "/dyma/s/dymax/020005/bg.tas" has changed and the
buffer was changed in Vim as well
See ":help W11" for more info.

Here is a dir/full of that file on VMS.  Perhaps a significant detail is
that the file is owned by [DV.BH] whereas I am [DV,BG].  Also, I have
seen the same dialog box appear when the text file is a "Stream" file,
so I don't think the fact that it is a "Variable" file has any bearing
on the problem.

BG.TAS;1                      File ID:  (33392,18,0)          
Size:          975/1035       Owner:    [DV,BH]
Created:    24-MAR-2005 11:03:10.80
Revised:    24-MAR-2005 11:11:47.76 (12)
Expires:    24-MAR-2015 11:11:47.76
Backup:     <No backup recorded>
Effective:  <None specified>
Recording:  <None specified>
Accessed:   <None specified>
Attributes: <None specified>
Modified:   <None specified>
Linkcount:  1
File organization:  Sequential
Shelved state:      Online 
Caching attribute:  Writethrough
File attributes:    Allocation: 1035, Extend: 0, Global buffer count: 0
                    Version limit: 1
Record format:      Variable length, maximum 0 bytes, longest 127 bytes
Record attributes:  Carriage return carriage control
RMS attributes:     None
Journaling enabled: None
File protection:    System:RWED, Owner:RWED, Group:RWED, World:
Access Cntrl List:  None
Client attributes:  None

Total of 1 file, 975/1035 blocks.

Any ideas as to what could be wrong?  Further tests I could do to narrow
down the possibilities?

Thanks,
Ben