Yes, Image credit to Gareth. Fix in Decaf seems to be this:
.label { background-color: #fff; color: #000; font-weight: normal; font-size: 100%; display: block; text-shadow: none; }
Thanks to one of our Moodle guys.
It just goes to show how scrupulous you need to be in managing details. On Wednesday when we upgraded I was paranoid about stuff like the editor which flunked in 1 out of three trial sites (And still is) so on our list of tests there was "Does the edit appear in the label?". I went back to my test site. In the 60 minutes of testing between the Upgrade Process and Yes the upgrade is OK, don't revert I started to add a label (editor was OK) and I never finished the process. Then 24 hours later I noticed the problem.
After the upgrade: nothing else except for cosmetics is now troubling our Decaf. We will be right up there when a responsive version of Awesome Bar, or some horizontal top nav comes off the production line.
-Derek