It just happened to me again on the DL forum:

From "GA didn't fill all of FC" (last post 5:12 pm)

Click Previous Thread

Go to "Flight 6128 out of DTW complete incompetence" (last post 4:35 pm), which was at least several threads beyond the "previous" one that I had expected to appear.

When I go back to the DL forum page that lists the most recent threads, I see that there were eight more that were between the thread where I was and the thread to which FT erroneously sent me when I asked for the Previous Thread:

"SYD-HGK now that there is no VS option" at 5:10 pm (SHOULD HAVE APPEARED)

"Homeland Security...." 5:08 pm

"DT TPAC...." 5:07 pm

"Any Diamonds...." 4:57 pm

"Minimum Connection....(SLC)" 4:53 pm

"Delta's Award Chart" 4:47 pm

"Testing the Delta SC..." 4:39 pm

"Update to DL SC...." 4:38 pm

before the thread that I was incorrectly taken to.