freebee, thanks for reporting this excellent find. To add a slightly different twist, when I ran into this situation the other day and called CS&S, the agent could not see the lower fare on her system at all, even though this was not a "web only" fare. She was still able to have the help desk book the "old" lower fare, however. ^ It took 20 minutes or more on the phone to book two one ways. (I wanted to book more flights but wasn't sure how deep the well of good will might be, and my other travel dates were not yet certain.)
So even if the fare displayed on the web site is gone from the system that CS&S uses, you should still be able to book it during the out of synch period.