African Violet has Long Slender Two Toned Leaves?

I have five African violet plants. Only the two with white flowers had lower leaves that were long and slender, mostly light yellow in the center with a thin edging of dark green, while their newer growth has come in with more normal looking rounded dark green leaves.

I recently snipped off the yellowy leaves (there were quite a few) and am now wondering if I did the right thing. All of my violet plants sit on a north window sill and may get only a few minutes of sunlight reflected off the building next door each day.

The three other plants get exactly the same treatment and their leaf growth is lush and dark green. I water them all when the soil feels dry and fertilize lightly maybe every other watering. Has anyone else experienced this? Was it a mistake to cut off those yellow leaves (they seemed healthy, other than their shape and two toned coloring)?

By BEK from Chicago, IL