" All software has bugs and one worrying statement I have heard is that sometimes a bug will take years to materialize. "
Absolutely NO.
All software does NOT have bugs. It's entirely possible to write bug free code if the right methods are used. Microsoft Windows clearly is an example only of how to get it WRONG.
What MAY take years to show itself is that the code might contain OVERSIGHTS ! It's almost impossibly difficult to test for every possible eventuality.