THis looks to be just slightly variegated. Nothing good or bad. just the pigments of the leaf differing. You see with more so with plants when they are babies and tend t grow out of it. look up some pictures of variation, and compare them to your plant to confirm. Otherwise shes looking nice and healthy. having a sticky trap is not a bad idea for prevention. Good luck!
calclium deficiency -- pH too low (way more often than high), nute lockout or simply too little Ca provided.... The first two often cause coinciding symptoms of other 'stuff,' so i'd go with low Ca levels as the cause in this case. It's 1 symptom and matches well. Leaf symptoms are not discrete, meaning more than 1 cause is possible and requires a process of elimination using more information when possible.
This started out as brown spots on big fan leaves and has turned into what you see on the pictures. I've been ignoring the discoloration until I was greeted by some wilted, dead leaves on plant #2 today.
I'm not worried at this point, just really want to know what's happening