It doesn't seem to be anything to do with their age as some are older and one was only published yesterday. There does not seem to be an explanation in the list at the bottom of the page.
sort by best latest
It must be something new as I haven't seen it before.
Yes. I'm not sure that I've really clicked on all the ones that are purple recently.
I wonder how long it takes if one does not 'clear the cache and cookies?' I don't even know what computer cookies are! I can clear up the ones at home quicktime!
Cookies are encrypted information saves like when your browser asks to save a user name and password. Cache is where frequently visited pages are stored. The links become purple and your computer will load a webpage from Cache if there an no changes.
I'm still checking, too.
I'll have to check and see if that is what has happened.
It's a puzzlement, so we'll just have to keep checking.