Good for you, keeping up the intensity. A decline in exercise intensity as we age is probably a lot of the decline in VO2 max with age. For various reasons, older people tend toward more endurance training, and moderate intensities. This obviously doesn't preserve your ability to go very hard all that much.

As for cadence: you're new, and newer riders tend toward lower cadences. It will probably come up a bit with practice. Spinning smoothly and quickly is a skill, after all. You would expect maximal cadence to fall with age, and I wouldn't be surprised if it extended to freely chosen cadence, too.

That being said, we have no way of knowing what type of rider you are. 80 really isn't excessively low, and it's possible that's just the way you're wired. Keep working at it, if only to preserve your motor skills as you age, but don't worry too much if your cadence at tempo is 80.