Yes I know, but the default saves do not update everytime I play? The default saves just recently appeared at the top of my saves list...perhaps I accidently deleted a default add-on or something to make them do that, idk
The launcher checks all the files for inconsistencies and will skip overwriting if there are no differences detected. However, when a change is detected it'll overwrite all the base files with the cached ones, which also updates the timestamps on the files. Chances are some random base file was touched by a mod or external program, prompting the overwrite.