They acutally could possibly be stretched with only 100 hours on it. Some made it more some made it less and the odd one never stretched at all. One of mine was done under warranty at 7,000 kms and the second one needed to be done at 14,500 kms. I did a complete rebuild on it then just cause. Things weren't in that bad of shape but I had the motor out and appart so I went thorugh the whole thing. If they are stretched bad you'll get a real loud ticking sound coming from the valve covers. Can be a little hard to distinguish from the clutch rattle but when they get bad enough there's no mistaking the sound.
The swelled rad is one that I did forget at the time. Had mine replaced as well at around the 7,000 kms mark. There's a white cap in the overflow that can either be drilled out a bit or thrown away. Everything would build pressure and swell the rad as a result of poor venting in the overflow.