thanks, Janet. I was thinking the same thing--that it looks like phlox.
ah, I just checked my 'no longer have' list of plants, and there is one phlox in the list right now:
'paparazzi sparkling blue'
and--that's it!!
I had forgotten I had that cultivar there last year, and hadn't seen it all this year so assumed it was gone!
thank you!!
good to know it has returned after all!!