Similar to asking why an athlete has a bead of sweat on his forehead, she looks very healthy, rigid turgor, tells me she is going hard, not too stressful, just right, its a thing of balance to maintain, between cooling over the long 18+ hour days, anytime a tip slightly curls up is a cooling thing, 10% of water used during daytime is for cooling, just cool her off a degree or two, or raise the light in 6" increments honestly she looks good. Nicely grown.