Sorry to say, 'Johnson's Blue' is sterile so either a) you don't have a 'Johnson's Blue' or b) eh, well there isn't really a b ;)

If 'Johnson's Blue' is the only geranium you have in your garden you don't have the real thing. It is very common to get a 'Gravetye' when buying a 'Johnson's Blue'. I should know, I bought 3 before I got the real one. If you have other cranebills then it must be some of them making your babies. They are notorius unfaithful so that explains why there is 1400 different named varieties today. And thats only the named :)
Please give us a picture one day, will you?

Thanks for the reply! Hmmm, me thinks I don't have Johnson's Blue, then. I will look up Gravetye. 1400 named! Wow. I knew there were a lot, but didn't know there were that many. Thanks again.

This is a good database to have when you want to get into the world of Geraniums :)

Your Geranium may even be x magnificum or as Ann Norway says himalayense and it's cultivars including 'Gravetye'

Here is a link that might be useful: hardy Geranium photo database

I have what was called Geranium himalayense and what was called Johnson's Blue and they I can't see any difference. I think that a lot of what is sold is a form of G himalayense and it does seed around. For me that is part of the fun of growing hardy geraniums, you never know what you will find next or where and the duds and superfluous ones are easy to pull up. Even if you have to do it sereptiously from the neighbours yard.
This apeared in a clump of Brookside this summer, it is a nice tidy 45cm plant that is still blooming now.

that looks like Geranium sanguineum 'Striatum'

How do I post photos?

Oops, you're right, I posted the wrong picture.

I'm still not convinced. Geraniums do sometimes throw a different colour during heat or towards the end of their flowering period.

Do you have closeups showing both flowers face on?

These are not sports in that they are complete plants with all the same flowers. They are volunteers and hybrids of the 20 different geraniums I have in this bed not sports like on roses where I have single roses of a darker red growing on the same plant that has very double light pink flowers. These are both probably a cross of G. pratense and Brookside or G. himalayense.
Leo

"not sports like on roses where I have single roses of a darker red growing on the same plant that has very double light pink. . ."

Leo: What you have isn't a "sport" but a rose that was grafted onto Dr. Huey. Your rose is reverting back to the graft. Time to get rid of it and plant something new.

It is a rugosa rose sent to me from The Devoninian Botanical botanical garden of the University of Alberta definitely on its own roots. They gave it to me so that I could give away suckers and keep this prairie heritage rose in circulation so I am sure it is a sport.
Leo