to commonly asked questions.

This keep popping up. Is this normal?

This keeps popping up on our screen. Is this normal?

This does seem to be a valid request from the operating system. It's asking your permission to make a change, most likely a password update or a request to update a small part of a program of some sort. Should be harmless. I'd enter the password in this case and move on. If it repeatedly over and over asks, then there's something else going on we'd need to address.
This image is a theme.plist hack