I was rejected in a similar way for my very first iPhone app many years ago. I wrote the Slicehost app, and it had a tab for managing DNS. I had a friend draw the icons for me, and for DNS I went with a globe. The globe my friend drew looked a lot like the globe used for switching your keyboard to another language, so they rejected me for that. I changed the DNS icon to something else and resubmitted and it was accepted.
The funny thing, though, is that I submitted two versions of the app: a paid version and a free version. They both had the globe icon, and one of them was accepted with it.
Perhaps they don't actually review all parts of all apps? Would make sense to do some sort of statistical testing. Unless you told anyone (and people started submitting 10 (identical) versions of every app) -- you could probably be about as effective as if you did fully check every app...
I think the real answer is that human beings are reviewing the apps. (Machines now at least check for apps making private API calls and stuff like that, but that wasn't the case in the beginning of the App Store.) There are a lot of different reasons for rejecting apps, and there are a lot of apps being submitted every week, so it makes sense for violations to occasionally slip through the cracks.
