similar opinion to redhelen.
My Father used to smack me occasionally, about once every 3-6 months when I had become a total horror and absolutely overstepped the mark. I knew at the time when I was doing it what I was in for. We have always had a good close relationship and I don't hold it against him at all - just wish I hadn't been such a brat.
However, earlier in the year I found an old diary and saw that he had hit me across the face when I was about 14/15. I had forgotten about this but obviously remembered it when I read about it and remembered the situation that lead to it. I actually found this very upsetting and struggled with it for a few weeks. Got over it pretty quickly though, decided not to speak to my Dad about it and it hasn't affected my relationship with him.
Food for thought though.