memcached plugin makes refresh of timeline ~14hrs in the past
technically I'm using an identical plugin that uses Redis instead of memcached, but one other person has had the exact problem with the memcached plugin proper.
This happens in both classic and Qvitter. If you refresh any timeline at the front, it will return a timeline several hours in the past. If you're using Qvitter, new notices show up on time above the old notices; if you scroll down, old notices are loaded using the past notices as a starting point.