Are you having any electrolytes while you ride? One of the things you lose is sodium when you sweat... so the salt cravings can just reflect that. You could try other drinks with electrolytes, but without as much sugar and coloring as Gatorade: Nuun and the "exercise hydration mix" from Skratch Labs. I like the latter (the "lemons and limes" flavor) best -- it is almost clear and the flavor is subtle. Anther option would be to take something salty with you as a snack, like pretzels.

w00t on the higher cadence and those speeds going uphill. IMO, that is a sign of fitness progress.