My cadence is related to how hard I am trying. On a club run mid 80s but a TT 100+. I think this is typical. The harder you ride the more you need to spin to avoid muscle fatigue.
Try riding at a very easy pace at a high cadence. It will probably feel uncomfortable.
BTW it took me about 12 months of riding rollers to realise you can stop pedalling and stretch without falling off. Its only when the wheels completely stop that you can fall off. Evennthen its very gradual, your wheels don't simply slide away from you. Its remarkably easy to stop pedalling for a few seconds and then resume. Aside from the limitation presented by the rollers width, it really is just the same as riding on the road balance wise.