Codeblocks should show this dialog only if the time stamps of the file differ from the time stamp the file had before codeblocks is going out of focus. So if the time stamp of the file is newer then you or codeblocks modified the file there is something other modifying the file (anti virus, drop box, other file sync things....)
Seems like CB itself is modifying the file. I have a bunch of code opened, saved it, had 24 hours go by without touching it and no message.
I added a few blank lines (pressed enter a few times and didnt save). Changed focus, come back and that window is up and timestamp is changed to today. Its definitely done by CB. Because the file retained yesterday's timestamp until I added a few lines in CB. Nothing else interacted with file, and I didnt save, so AV or whatever else on the PC still saw it as yesterday's file, only CB knew of the changes.