Durrr Treasure Chests

I was farming Upper Delkfutt Gigas on the 10th floor for their nice gil drops as THF/BLM (along with the Thunder Elementals that spawn there and Mimas for a free 8k Huge Moth Axe) and after getting a Delkfutt Chest Key, I went back down to floor 9 (Middle Delkfutt) to open a chest (which was a Tourmaline instead of gil, sad day).

Well, about 20 minutes later another chest key dropped. I continued killing stuff on the 10th floor and came across another chest. Enjoying my good fortune, I attempted to open the chest. Well, I got the message "This chest was merely an illusion." And it disappeared. I still had my key, though.

Soon after, I came across another chest, and the same thing happened. It suddenly dawned on me that Square-Enix must have made an update where the same person can't open contiguous chests? Or maybe there's a time-length where you can't open another chest in the same zone? I searched through the Updates history of FFXI and found nothing of the sort, but I figure that's the case.

Regardless, I think that, while I see the merit for this update, it severely limits the amount of gil/hr I can get in Delkfutt. I've considered going back to farming Sheepskin > Sheep Wool > Wool Thread, but I like to shake things up a bit from time to time to break the farming monotony.

I don't want to level my THF, but I really should. Sigh. :(