It gets plenty cold here but I think you may be on to something- they probably did germinate and then froze. We do get some wild temperature fluctuations in late winter through spring.
I believe I will divide the clump in the photo this summer when the foliage starts going dormant, I would like to spread them around the bed some so that bright patch of color is distributed throughout. I received that plant a few years ago as a pink one, and after 3 years waiting for it to bloom it turned out bright red. Oddly last year that one coral bloom showed up among them! Later I picked up a "red" one at Lowe's for my bed of fire colors- wouldn't you know, it turned out coral! I've moved it 3 times now, but a piece always shows back up. Once you've got 'em, you've got 'em forever! LOL