[Therion] Scale dependent "scrap outline intersects itself" warning

Hi, I have noticed that when producing pdf output at some scales, I get a warning that a particular scrap outline intersects itself, while at other scales the same scrap causes no warnings. eg, base-scale 1 1000 scale 1 4000 I get: [Warning: scrap outline intersects itself in scrap scr_jfacct_6@48h-i12-40-qikeng.tianxing] while if I change the scale: base-scale 1 1000 scale 1 1000 I get no such warning. To me this seems very strange. What's going on? Duncan.