Hi SL, welcome... Here's some literature on high bone density and it's causes.  However, I'm not sure your score would be considered abnormally high, since it's not too far from normal, if these numbers are correct.  Osteopetrosis is one disorder that causes high bone density that is caused by a problem within the bone resorption phase that can lead to dense malformed bones.  To be sure this is what the Dr. is suggesting, unusually dense bones, ask about your scores again, even though it does sound like you have the dxa print-out in front of you.

We rarely get questions like this, because most are worried about low bone density, so I would follow up with your Drs and maybe even get a second opinion.  The x-rays are a good thing to have if the Dr. is looking for more info, and your insurance will pay for them.  At least it will give you a better idea of what might be going on.  You'll probably be tested for some other things as well, but that's just a guess. 

Where both scans done on the same machine and same tech?  If they weren't there could be a discrepancy within the scores.

Here's a chart that gives examples of raw scores in g/cm² from the Univ of Washington's Bone Physiology Course.

Just for clarification, the World Health Organizations (WHO) definition of T-scores are as follows:

Normal bone: Any score above -1.0

Osteopenia:  Any score between -1.0 and -2.5

Osteoporosis:  Any score below -2.5

You can look at the above chart link, from the University of WA, to see both t-scores and raw scores in g/mc².

If I misunderstood the question, or if you could provide more information, that would really help.  In either case, you need to double check this with your Drs to be sure this is what they are referring to.

Good luck and we'd really be interested in finding out what you learn, on this, since this question doesn't get asked much and we could learn from your experience.  Also, if you could provide your t-score instead of the raw score, that might help.