[codewright]

Mumble mumble mumble eventual consistency mumble mumble sharded MySQL mumble mumble

[surferbayarea]

This isn't a case of eventual consistency. They don't bother to update the cache(if that is the reason) or update the database used in newsfeed. The deleted posts persist in the newsfeed database many hours(maybe forever) after the delete event.

[codewright]

Caching is a conscious decision to take advantage of eventual consistency.