I think it's so cool that when it pops up elsewhere it's welcomed. In the 15 years I've had it in my garden it's said propensity to be invasive hasn't materialized though it has moved a little. It's location coupled w/ garden maintenance may contribute to it's containment. It blooms early, topples out at 12 to 15 inches appx. and then basically becomes a non-factor as larger plants overshadow it's presence... at least that's my perception.
Caution may be advised as it is, after all, a wild phlox, but I like what I've got and I'm glad I got it.