I had bought one of these little plants at a rock garden plant sale several years ago, it just labeled 'alpine violet'. Like you, I couldn't resist the pretty little blossoms. It was intended to live in one of my alpine troughs. However, it hopped the curb so to speak and this plant became my nemesis over the years. It was popping up everywhere & I found it was difficult to keep on top of. It would probably make a good ground cover though.

Of course, all climates are not the same, and something that is invasive in one place may not be in another. That said, the true Viola labradorica does seed around gently for me, and in some climates (mainly northern, like yours) is invasive. More often though, a very aggressive, invasive impostor is sold as V. labradorica with variegated leaves.

Viola pedatifida would be a pest for me in my troughs, if I didn't remove the spent flowers and cleistogamous pods. I would keep a close watch on any viola species.

Thanks to everyone for all of their help and information, it is very appreciated!
Donna