... Major Snippage Has Occurred ...
The roof decking will dry out from underneath. It will even dry out somewhat through the breathable underlayment and shingles.
Google the matter and you'll find all sorts of discussions in construction and roofing forums. Overwhelming consensus: While most roofers will do their best to cover the decking as soon as possible, its not always possible or practical. Wet roof decking is not an issue...unless you're the guy that has to walk on it the next day. ;-)
BTW...covering the deck not only keeps the deck dry, but more importantly in a re-roof situation, keeps the interior of the house dry. I have T&G roof decking. A rainstorm on that deck would mean a lot water in the attic.