Right-click on the Borderlands2.exe file (most likely in the Steam directory a few levels down under Win32). Then look at the file version number. That is the number being referred to, and it changes for each update.
I've seen a few messages like this, but I just tested it on my Mechromancer and it worked fine. Not sure why mine would be unique on this. The only thing I can think of is that I am using one of the healing skills (that only heals a little bit) and maybe that triggers the full heal with the trainer.
If that's not why mine works, then I have no idea. Seems great to me.