Figured it out. I clicked on the trash can in the bottom center. I would not have known this other than mousing over it said toggle, so I figured it couldn't do more damage. But it turned it off and I'm good now.
While Camera Raw is open, if a photo is marked for deletion, there are a few ways to un-mark it for deletion...
1. With the photo selected in the filmstrip, click the delete (or backspace) button on your keyboard again. The delete key should toggle the marked-for-deletion status on and off.
2. Cmd/Ctrl + Z to undo
3. Right/ctrl click on the photo's filmstrip thumbnail, or on the main image to bring up the contenxtual menu and un-check the "Mark for Deletion" menu item.