D’oh! I was wrong… something did change! The client changed her Constant Contact password, so the plugin wasn’t talking to the Constant Contact system.
Possibility for future versions of your plugin: Though the password was wrong, the plugin wasn’t picking up on it. It event had that little checkmark next to the password as though it was all still cool. Could you have it check and confirm the credentials? Perhaps as an auto-first step whenever it gets upgraded or just every now and then? Just a thought for you…
Thanks!!
Suzan