Version 1.4.4. This happens whether you're switching between different Quests (clicking on individual quests) or browsing Puzzles - notably, this doesn't appear to happen with Labs.

What happens is the puzzles from whatever I was just browsing show up for a fraction of a second before the correct puzzles show up. For example, if I load Just for Fun and go back to Puzzles, the Just for Fun puzzles show up first for just a little bit (and the same in reverse). Or if I load Just for Fun and go to 3D Expo, the Just for Fun puzzles show up first (and the same in reverse).

I think it's relatively minor, but I still wanted to point it out.