Just checking one possibility...you didn't dig another rose out of that spot before planting the snow pavement did you? I did this with a Morden Pink and the roots that must have been left have sprouted and sent up canes into my Winnepeg Parks rose.

No, it was a new garden 4 years ago when I planted it.

I just noticed my subject 'shange' I wonder what that means?

I'm not familiar with this rose. Could it have been grafted and you're seeing the root stock blooming?

That is what I suspect.

It would be most unusual for a Pavement rose to be root grafted. Snow Pavement is actually suppose to be a pale lavender. So pale, in fact, that some years mine actually looks white. Some years, it is more of a pale lavender/pale pink. It tends to show the color when the buds first open. I think perhaps weather, rainfall, fertilizer etc affects it?
Jan