Deadlift is one of those weird lifts that you can lay off for a few months (assuming you're still lifting, squatting or whatever) and come back and not seem to lose any ground, or even be stronger at it.
But if I don't do flat BB benches for a few weeks.... my bench has suffered when I come back to it. Why is that?
Anyway 645 without a belt is pretty massive any way you slice it!