Time to tell him... and have him change up.

Maybe he has fantasies, old or new, that he really hasn't explored. Things that, though you might know you're safe, might push at your boundaries and be, in fact, a little scarey.

What about your "firm" limits (hard but not quite in concrete) that maybe it's time to explore... the ones that scare you to admit you just might like to try.

Just a couple of thoughts on how to approach the problem.