It's really not a prior art issue IMO..it is an "obviousness" issue...different from showing the examiner that what you have in your claims is not similar to what a prior patent has in its claims...this is an examiner saying,yes you're right Mr. Moore, those claims of yours are different than the two individual ones we are ciitng, BUT...a person with reasonable background of these indivdual claims would have combined their two separate patents and made what you claim...an obvious next step..., therefore un-patentable. It almost comes to a perception argument based on what the examiner believes is obvious against what we will claim was not obvious to either of the other patentees when we submitted out patent. IMHO