I think the time the account was past due is important here. I know Linode gives 10 days (IIRC) but I'm not sure about DO. I did have a DO account go past due over a holiday weekend where I wasn't paying much attention to email notifications (I have a dedicated card that I only put small amounts of money on for online use) but luckily I didn't suffer this fate. I don't think it's unusual to have something as low as 3 business days until an account gets axed in hosting though.