by Ken Task.
Probably related to a combination of Moodle cache and/or iAPC or PHP OpCache. When ever I have issues with a 2.x now-a-days I clear server cache ... in Moodle and in APC or OpCache. Rebooting server probably did that.
IMHO, there are certain things in M2.x where purgecache should be added to the routine such that admin user doesn't have to remember to do so. But, then again, that's what makes life for a Moodle Admin level user interesting, huh? ;)
'spirit of sharing', Ken