[jacquesm]

> All of the plastic deformation of wheel components should happen at build time.

I suspect this is true, except that parts being what they are (always with small inconsistencies) and the spoke nipples riding inside the rim and j bends in the spokes riding inside the holes in the hub tend to 'find their spot' after being exercised for a while. I've made it a pretty hard rule to re-check after 6 weeks and invariably something has shifted. This probably indicates that my wheel building technique could be better, then again, I've never had a wheel that I built fail - so far - and over the years have done between 100 and 200, some of them for very heavily loaded bikes (tandem trekking bikes).

Most recent wheel was actually this weekend, I'll be sure to give it another really good look to see if I missed something that might cause this which I can catch at an earlier stage.

My typical wheels: double walled aluminum rims, quality spokes and nipples (and the latter seem to be hit-and-miss, I've had bad batches of nipples more than once in spite of re-ordering the exact same kind, but I noticed it immediately during assembly), typically Shimano hubs.