A little more info:

Well, I called a Travel Agency that uses worldspan and that Agency was able to pull up this fare. I also called AA reservations. They were unable to find the fare. The reservations agent said that SP might mean special fare. She was of the opinion that since she could not pull the fare up in Sabre, that this was an unpublished fare. However, this fare doesn't have the restrictions typical of what are normally considered "Unpublished fares" nor is L-class the usual booking class for such fares.

AA's customer service policy does not say anything about published or unpublished fares, though I would imagine that they would claim that there lowest fare policy only applies to published fares. The question of whether loading fares only into Worldspan is a violation of AA's Customer Service Policy could hinge on whether this is a published or unpublished fare. AA could contend that a fare is not published until it is available in all of the GDS. I would contend, however, that a fare that is loaded into one GDS and is available through all points of sale in that GDS should be considered a published fare.