Event Date Stamps Messed up?
So this issue was quite obscure but I went through my wordpress plugins one at a time, deactivated and tested and this one: "Social Icons Widget by WPZOOM" was at fault!  Once I deactivated that plugin, events started to work correctly again.  This plugin was part of a recent site update on our test, it apparently passed all the tests and was promoted to our production system.  Time to check the testing checklist again.