How does pagination on Reddit's home page work?

Reddit uses a time decay algorithm. That would mean the sort order is subject to change. When a user goes to page 2, is there a mechanism to prevent them from seeing a post that was on page 1 but was bumped down to page 2 before they paged over? Is it just an acceptable flaw of the sort method? Or are the first couple of pages cached for the user so this doesn't happen?

Side note: It's my understand that Digg cannot suffer from this issue but that HackerNews and Reddit can.