So it's just a "feature", is it?
No way of switching it off?
It's not a problem with WinZip - The files have
been changed simply by opening them and WinZip is simply asking if you want to save the modified file or save the existing.
To avoid this, extract the files to a folder, edit them and then re-archive them.
Windows has featured "native zipping/unzipping" since XP but, it doesn't work with all archives and can corrupt the data in some instances.