Any frame material is likely to fail over time. Steel rusts, y'know.... As long as you don't see any cracks it should be fine. I'd do a basic visual inspection of any bike I use, of any age, on a regular basis -- every 1000 miles or so. It will still likely outlast your usage / ownership of the bike.

The only material I'd have any real concern over would be 1st generation carbon fiber. I believe they understand CF much better these days as a frame material.