In my climate, it is not at all unusual that bigleaf hydrangeas will continue to push buds and flowers until it becomes too cold for them to do so, especially those that have the bloom on new wood feature.

well that makes sense, these were on new wood too.

I have some that only bloom on old wood and which produced new blooms this year. One is blooming and the other two will probably open the blooms in several weeks.

The 'rebloomers' have yet to open new blooms but they still may. Temps are finally moderating into the lower 90s and that would be the time for them to open new wood blooms.

my paniculatas are still pushing flowers here in zone 5

I have new blooms on Nikko Blue, Everlasting Summer, Fuji Falls, Kluis Superba, Lady in Red, Izu-no-hanna, Ayesha and a couple others with no names. There are even one or two new blossoms popping on the Golden Crane (Hydrangea angustipetala 'MonLongShou') that has been in bloom since early spring! Golden Crane is fairly new and there is not much history on it so every day is a new experience. About half the plant is 3.5 feet with the other half shooting straight up to 10-14 feet! Early spring the blossoms were so fragrant that it could be smelled in the kitchen - these older blossoms have just a hint of perfume.