Happens to me all the freaking time. I haven't been able to reproduce it to a certain section but I have noticed it alot with the wifi button and hitting the spacebar key. WTF. I'm losing patience with this i5 and i'm this close to returning it...
I think there is 2 things going on here from what Ive read in various places and experienced.
First the sliders to turn wifi on/off etc behave slightly different in ios6 than 5. This was the same on my iphone4. The tap doesnt seem to slide them the same as it used to.
Second, ive noticed that on legacy apps (non resized apps that are letterboxed) near the edges of the letterbox are not as sensitive as they used to be all the way to the edge. I have to hit the space bar slightly higher on old apps vs how I did it on the 4 or on resized app's keyboards. Other games that have controls near the bottom edge have the same problem for me. Its like they either didnt extend the touch responsiveness all the way to the edge of the old app or that touching outside the app edge with part of your finger disables the tap.
I've seen this too on a few random occasions. For the bookmarks button in Maps and a few other random places (takes multiple taps to register). I can't reproduce it, however, so I'll wait to see if it gets worse before thinking about bringing it in.