And that first time will decide about whether or not there will be any other first times.
The first time someone asks for a refund.
The first time someone criticizes your work.
These situations will either make you or break you.
Here's the thing...
If you insist and focus on telling people (and even more importantly yourself) that this is the first time this happened, that it's not your fault, instead of really listening and trying to improve the situation, you'll end up making it a bad habit.
It'll turn into a bad habit because it works.
Most people will walk away if you tell them that it never happened before. They'll feel like something is wrong with them. But even worse, you'll also start to believe that it's not your fault.
But it's just a quick fix.
Until there's nothing left to fix anymore. Until the first time turns into a downward spiral of many more next times where you tell yourself the same story again and again. That story that it's the first time and that it's not your fault.
Try to make sure that that first time isn't the beginning of your last time...
[Related: I stopped giving a shit a long time ago]