But in general, the way you tend to end up with wearout is through electron migration ("electron wind") which is damage to interconnects from electrons slamming into metal atoms over and over and slowly ripping apart the wires. Modeling electron migration correctly is really hard, but (from memory) a general relationship is that voltage linearly increases failure rate and temperature exponentially increases it. The constants for these models are determined empirically and, of course, are NDA'd.
In general, I wouldn't worry about it. The MTTF for semiconductors is already very high even under awful temperatures 100+ C, and so as long as you cool it properly you'll be fine.
> would it be expected that a non-zero amount would fail?
The failures you describe here are going to be due to setup time violations. These issues shouldn't be transient (assuming identical temperature and voltage) since the performance characteristics of an individual device don't really change over time. Of course, the issues can seem transient as the failures may not actually always cause noticeable corruption (maybe you generate a wrong FPU result but that specific path is only exercised under rare uarch conditions).
So, it's a non-answer, but: yes and no. Maybe your chip is perfectly okay and never has any violations at the parameters you selected. Maybe it does. Neither you (nor in fact the manufacturer, though they do have a better chance since they know the process/design) can ever really be sure--all that's left is empirical burn in testing and hoping for the best :)