My beet leaves are fusing together! Is this a Normal Thing? (Indoors, Boston, MA.)

My beet leaves are fusing together! Is this a Normal Thing? (Indoors, Boston, MA.)

This is a beet that I pulled out of the ground and potted up. The newest leaves at the center are sticking straight up and are fused together at the edges for the first couple inches. I don't have a photo of the newest development, but now all the new leaves form a fused ring around the meristem, so even newer leaves are growing into a small cavity they might not be able to get out of.

I suppose I should just chop off and eat these leaves so they don't strangle new growth, but is there something else I should be doing? What causes this?