I found the answer - in Preferences > Files
I guess I am going to have to ingest again to get these files back to 300 dpi
You can use the "Change Resolution..." command in the Tools menu instead.
Here is the solution for others that may be having this same issue: You can either instruct PM not to do this at all, or you can instruct PM to set the resolution to 300. To do either of these, open up the Preferences dialog, click on the Files tab and then either uncheck the "Add Photoshop resolution info to Camera JPEGs during IPTC update" or change the value in the field labeled "Default image resolution to use:"
-Kirk