Critical

So here it goes.
This weekend I went to a xmas party and decided to take my camera.
So I'm walking around shooting away, and got home with about 190 shots. After deleting the bad ones it's about 160. Not too bad.
Most of the 160 are in my eyes "OK" pics, a little adjustment here and there and everybody likes them.
Some of the pics even say something, wow, I'm getting better.
Two pictures stood out, and I really thought I had a winner there, but then I looked at them on the computer, and sure enough, the focus is not perfect, darn. Granted, prints up to 5x7 won't show it, and I'm not even going to print them at all, my friend might (since he's in them), but the fact remains, I am not as happy with them as I was before I noticed the focus, or lack thereof.
Some might say, better luck next time, others, at least you got the shot.
What bothers me is, that I could have done it better, if only I had taken a little more time. Yes it was not a photo shoot, and most pictures were made without planning and spur of the moment.
Still it bugs me. I just need to learn to slow down, but how do you slow down in a situation like that?
Besides the fact that they are slightly out of focus, am I too critical with myself. I understand that, to get better, I need to find the flaws and figure out a way to do better next time, but shouldn't I still be as happy about the pictures after finding the flaw, as I was before?
I don't know..., what do you think?