The cars do come with a rev limiter, so an occasional miss shift usually won't hurt anything.
When I first got my STI, I was unprepared for how fast it got to redline and pinned it to the limiter for a second. It happens all the time on my motorcycle, and the redline there is 12500 rpms. Like other have said, I really wouldn't worry about it. If you bend a valve, you'll know pretty quickly.