How you maintain your business relationship with your client is up to you of course and involves more variables than we have access to, but I'd suggest rather t

How you maintain your business relationship with your client is up to you of course and involves more variables than we have access to, but I'd suggest rather than thinking about charging them more per hour (unless it's a weekend/holiday/after-hours) make sure you never charge so few hours because it's super annoying for any developer to drop everything and work on a new project for just 2 hours of income. And this isn't a dishonest recommendation. If they make some error, try and figure out a way to prevent it in the future: whether it's a better deployment script or something else that works to prevent this class of error.