I have loads of knobblies, including the same Meadow Green one as yours Nic. I don't think your flattened rim is an issue. Most of the straight sided ones (i use that term loosely) such as the 9610 seem to have flatter rather than rounded polished rims. Of course they are not symmetrical by very nature of the design, but if you mean that yours is fire polished but has a flattish appearance then that seems to be the norm. If however, you are saying that it is flattish and ground (like the top of a Hambone vase for example) then that might indicate it has been tampered with - but it doesn't look like that has happened from your photo. Emmi