I AM NEITHER A LEGAL PROFESSIONAL NOR AN INSURANCE PROFESSIONAL. THIS IS JUST A PERSONAL OPINION FROM A STRANGER AT A WEB SITE:
There is almost always a grace period; I think 30 days is common. In some cases it's legally required. It may not even be an issue in your case. I suspect the draft payment is processed a few days before the due date, so that the accident may well have been in a time period covered by your previous payment. I'm assuming you took care of the premium payment as soon as you found out about the NSF.
Crystal