I would say its a cal mag problem from the looks of it. Doesn't look like pest damage IMO, just because you find webs doesn't mean they are from mites, could be normal spiders. I have them on my plants all the time and just let them live there and kill other pests.
Gotta agree wit hells canyo on this one. It's always good to check for mites, even when you don't see damage, but trust me. It's not mites. I know mites all too well.
If you're growing outside you can just blast them off with a stream of water. Indoors, hold the plants sideways under a sink or bathtub faucet to wash the little SOBs down the drain, or vacuum them off the leaves with a Dust Buster. There's some pesticides you can also use. I stopped an outbreak a couple months ago with a combination of spraying and misting water and applying spinosad (Capt. Jack's Dead Bug Spray). Apparently mites don't like to get wet. Also, they breed and eat faster when the temperatures rise, so try to keep your plants cool as possible.