It happens. Not to all varieties, but I see these root suckers quite often.
Dibleys used S.kentaniensis in their hybridization to keep the size of the plant compact and extend the blooming season. Crystal series are quite close to S.kentaniensis. Do not know about "Hannah" for sure - but being close to the species probably increases the ability to propagate in this manner. I would say - the same varieties that create lots of baskets - new plantets on the flower stalks also produce root suckers.

I.

Thanks, Irina. I recently added eleven new streps purchased from Dennis Miller to my "collection of one" so have an even dozen. As these grow and bloom, you can expect more questions from me.

Dave,

As Irina said it does happen. This is a plant of Dale Marten's Texas Hot Chili which was doing the same thing when I went to repot her a little while ago.

Chris

Here is a link that might be useful:

I have Nerys, which is a Dibley's variety, and it does this as well. I have even had plantlets sprout from the drain holes in a pot of Nerys. No other varieties I have do this.

Karen

Great thread. I have several from Dennis Miller and they are all great plants and have bloomed continually. I also have Texas Hot Chili and Nerys, so was glad to see the input on those.
Chris, thanks for that great picture.