Watch a file for changes

I'd like to watch one specific file within a folder on a server (connected via AFP, but not always connected) and be made aware of when the file stops modifying for more than 10 minutes (or so).
I have a log file that writes to itself - when it finally finishes, it stops writing.
I'd like to be alerted when it's finished.

The filename is always the same.
The contents vary, but at the end, I DO have a consistent message that is output, that I could use to fall back on if modification time doesn't work.

Any suggestions?

Thanks

How about "date last modified is not in the last 10 minutes"?

hoo boy... CLEARLY I'm showing my noob skills on this.
Of COURSE that is how I solve it. I guess I didn't realize 'Date' could go down to 'minutes'!!

Thanks,
Jeff