Thanks for the links.

The second is about two years old and I don't see any mention of the tips being removed after previewing.

The first is about three years old. It does mention that the tips were removed after previewing.

I'm reasonably certain the tips were there after previewing (just a week or so ago).

Regardless of whether they were (accidently?) removed recently or haven't been there for a long time, perhaps I can just request that they be reinstated (i.e. make SoPW work the same as PerlMonks Discussion currently works).

Well, look at that! I just previewed this post and the hints are no longer there. Perhaps they only disappear for responses but not for original posts. Anyway, could we have the tips for all sections irrespective of OPs or replies.