A user threw up an interesting issue with this today. When a particular user updates an entry on a list with a append field, but doesn't put anything in the append field, the version history shows a blank entry but it doesn't appear when anyone views that entry in the field itself. Anyone else it does appear.
Googled it but only one relevant link came back. This really just confirmed that a when you update a list entry that has an append multi-line field then if you don't put anything in the append field it puts in a blank entry automatically. A version history entry is created showing the blank entry but nothing appears in the main view ofd the entry.
Posted question about this to EggHeadCafe.