New Primary in Remaining Kidney?

My husband had scans in October when he finished his 5th cycle of Sutent - 50mg 28/14 (following a left nephrectomy mid-February, 2013). When the 12cm tumor on his kidney was discovered, they also discovered "innumerable" and "too many to count" nodules in both lungs, as well as some bone involvement.  

The good news is that he continues to have shrinkage of those lung nodules and is down to fewer than 5, all under 5mm.  They also believe one of the ribs they originally thought was cancerous was actually a mass near that rib that lit up, but has also reduced to where it is no longer visible...at least that is their explanation as to why the 8th rib no longer appears cancerous.

At the time of the left nephrectomy, there was a 5cm simple cyst in that kidney and they also noted a slightly complex cyst in his other kidney. I continued to question them about that cyst all these months.  This last scan clearly said, "This is not a simple cyst" and further evaluation should be done. It is now being referred to as a mass or lesion depending on who we are talking to.  Although it has not changed in size (5cm), it is changing, i.e. thickening septations.  The rcc oncologist is confident it is a primary secondary rcc rather than metastasis from the tumor in the left kidney. He commented if my husband hadn't already had his one kidney removed, they would be removing this one.  

Can he really assume it is a second primary? I feel like we accept what we are told and then later as time passes I think about it more and begin to have doubts...  He is seen by not only a VA oncologist, but also an oncologist from James Cancer Center that specializes in renal cell cancer.  Am I in denal or do I just need reassurance?