Just pulled the lash adjusters out of my 2007 4.6 3 valve. Looking down into the bores (all of them) reveals what looks like a opening worn through the bores. These are not uniform for each bore but do appear to be a pattern from front to back. The lash adjusters do not appear to actually contact these areas. Is this normal? are these cast into the bores to drain oil back? The engine is supercharged and has less than 30K miles 50K km.