Big lily plants

I planted some lilies a few years ago (sorry, can't remember the varieties) that grew to their expected heights of between 0.8–0.9M. They tended to produce a couple of flowers each.

This year they're all growing taller, with the ones in the best sunlight already at 1.4M and still looking nowhere near ready to flower. They're also developing loads of heads — 10 at least but some with 15 tiny buds so more may appear yet.

Is this normal for lilies, both the height and number of flowers, and the way they've taken 3-4 years to suddenly grow bigger?

Or is it just a good year for lilies?