Yes. The PR update is actually a snapshot of an amorphous process that is continuous. So you might lose 3k links today, and still be technically a PR 2 visually but in reality might have dropped to a PR 1 status. The same is true of the opposite; you could gain 15k links (lot of effort or press release, etc) and will have the true PR 4, but must wait until the next static update.
Why is everyone here missing the big picture? So many people are saying "Enough backlinks." Have we forgotten than the amount of backlinks does not matter? It's all about the quality of the backlinks. Obviously more can be better, but you can't say "I have enough backlinks to be PR4."