I use the FF schedule, (G-M-B) and don't usually see nute burn curl the leaves, but do see some leaf-edge burn on occation.
I kinda like the foliar overspraying or the high humidity possibility. But, you mention nothing of leaf burn...

Watering can cause a spike in humidity, too. (plant transpiration and soil moisture evaporation) Especially if in a confined area. Since no mention of mold tho, and only afflicts one plant...

Do you have adequate ventilation, and is the 'problem' plant subjected to more heat than the others? (closest to lamp, in a 'dead-zone' getting no air...)