Yeah I've got a couple little spots on the very bottom leaves on a couple of mine. Could be a number of things but your leaves look very healthy. Most likely just old damage.
Calcium deficiency.... that doesn't mean you need to add more necessarily... may be watering practices, nutrient ratios, ph possibly salinity as they look a bit over fed.
Calcium deficiency.... that doesn't mean you need to add more necessarily... may be watering practices, nutrient ratios, ph possibly salinity as they look a bit over fed.