It's a wild world we live in that we can BOMB our own body parts. My guess (not supported by any medical education whatsoever) is that, so long as you're not getting any pain from the steel pieces now, they can float around in there indefinitely without causing any particular problems - they're no different really from shrapnel and I know doctors will sometimes leave that in there. They might even work their way out on their own eventually. That said, if a new doctor is going in there to work on things, I'd have him yank the extra parts while he's in there.