I posted my guess before I saw your answer. Honestly :-). It is good to blame the manufacturer, and you are probably right, however, if you jar the roll of cloth you can sometimes introduce this stress yourself (or UPS, or the trucking company, or your supplier, or anyone along the line could do the dirty deed). This is one of the reasons you should not store your roll of glass on end.

> After wetting out the cloth I noticed that there were a series of ridges
> that were beginning to pucker ever so slightly. I babysat the wetout for
> quite a while, hoping to be able to squeegee the puckers flat as the resin
> cured. This was only marginally successful and I ended up with what you
> now see. The blame for the puckering lies with the weaver - I am assuming
> that the tension settings must have been unbalanced.