Dripstone stalagmite can generate on surface above grass

A dripstone stalagmite generated above the ground

What I expected to happen was...:
I did not expect a dripstone block to appear on the surface with no cave directly in contact with it

What actually happened was...:
Dripstone blocks appear just above where grass blocks would be

Steps to Reproduce:
1. Opened the world, seed is 3589527422406707519. Location of bottom of feature is approx 371 106 -239