Your daughter was given the relevant "punishment" for forgetting homework, or whatever it was that caused this behaviour mark. It was issued correctly, and if she feels it was not, I'm sure she can discuss it with the teacher that issued it.
In regards to it being fair - it is. Whether she wants to accept that or not, is her choice, but the system should and I hope is treating all students fairly and issuing points correctly when and as needed. What would have been unfair is if she was being penalised for certain things that other students would not be penalised for - but that is not the case.
I think the worst thing you can do right now is add to her feeling of it being unfair. Instead, help her understand why it happened and that it's not a big deal but you hope this is something to learn from and move on. You continuing with the "woe is me" attitude for her is the worst thing you can do and no offence, that is what is being picked up from this thread.
Help her learn and move on from this. You've mentioned that she doesn't get rewarded for good behaviour, if she's overall a fantastic student, does she expect a parade every time? The fact this is her first behaviour point shows that she is a good student and doing her best. That is all that any parent and teacher can hope for.
Most teachers will always do their absolute best by their students and whether they consistently praise each student or not, they are aware of what student is doing what.