Q:

Mixed conditional: Past simple + present simple

I have just read a sentence like this:

If I behaved like this, I owe her an apology.

This construction (past simple + present simple), that sounds perfectly natural to my non native ear, seems some kind of mixed conditional that I have never seen on my grammar books. Probably it is just not a conditional at all, because it is actually possible that he or she behaved badly. I would love if someone could shred light on this topic. 

A:

Mixed conditionals are very common in actual usage.  The numbering of the conditionals leads learners to overestimate the frequency and importance of the canonical forms.  
Another thing that is sometimes missed is that where you have if+simple past, that doesn't always represent an unreal or counterfactual present or future.  Sometimes it represents a real or potential past, as in this case.
So there's a distinction between the canonical second conditional, in which the simple past represents an unreal present (If I was/were there, I would be happy), and an alternative interpretation in which the simple past represents a real or potential past (If I was there, I don't remember it) - as contrasted with an unreal or counterfactual past, which would use the past perfect (If I had been there, I wouldn't have remembered).

If I behaved like this, I owe her an apology.

In this apology or half-apology, the simple past doesn't refer to a counterfactual present or future, but to a real or potential past.  The main clause verb (owe) is simple present because the apology is owed now (having presumably not been given at the time).

