question about message received while reorganizing LR4 catalog

[mapgirl]

I was saving my "Metadata to Files" when I got the following message: "one or more of these photos has been changed in an external application. Should Lightroom overwrite the settings on the disk?"
I am currently using Lightroom 4.1. I used to use Lightroom 2 and I do use Photoshop Elements for some external editing. What happens if I say OK? Will I lose the edits I made? Or is LR4 updating from LR2?

Thanks for the help!