Follow up DRE after surgery?

What's the need for regular follow up DRE in addition to followup PSA tests after prostatectomy?

I just read a statement from a respected doc that after RP we should be getting both PSA and DRE followups every 3-6 months (3 months if Gleason 7 or higher; six months otherwise.) The DRE would be looking for nodules in the prostate bed, obviously, since there's no prostate to prod. I've been getting the PSA religiously every 3 months as my doctor instructed, but wasn't asked to come back for DRE's or any other kind of testing.

What have you all been advised to do?

At my first post-operative visit, I asked my urologist why he was doing a DRE.  He gave some explanation about feeling the area where the prostate formerly resided, looking for anything unusual.

Personally, I think that maybe they just like to do that. 

They are looking (feeling) for other things during the DRE exam...internal hemorrhoids [sp?] or other growths or cancers of the rectum, for example.

Should be part of regular physical exam, prostate or no prostate..