No, go get it exchanged and keep going. Only count time that it was at a full boil as boil time. So if it boiled for 20 minutes and then stopped, but it took you an hour to get the new tank hooked up and the boil started again, you still only count 20 minutes so far and boil for another 40 minutes. Your beer will be fine.
Also, what above poster said. That or go electric.