When you have a really high contrast scene, like the one Aggie is describing you can get highlight bleed when using a staining developer. I first noticed this when scanning some 6x9cm negatives. Cutting back on the development time and agitation helped but never completely eliminated the effect.

With high contrast scenes I have had better success with compensating developers, and D-23 works well with most films I use (TMAX and APX100). I dilute D-23 1:1 and develop for around 10 minutes followed by a 4 minute bath in either Kodalk or Borax. 20 Mule Train Borax from my local supermarket works just great and can be had for a great price.