I've had this vine for over 15 years now (it was about 10 years old when I got it) and it has been flowering wonderfully every year. This spring is was full of blossoms like normal and when they dropped off the plant leafed out like normal as well so now it is very bushy. However now I see more blossoms on it; not like the spring, just a dozen or so new blossoms that weren't there last week. I've never heard of wisteria flowering twice, what would cause this this?
Quite common for Wisteria to have a few late flowers. Might be more than usual if perhaps pollination failed the first time?