I don't see any dishonesty, but you're right, it doesn't seem that they answered your question. You asked them to comment specifically on whether a density of ~150 grafts per cm sq. was possible. I would draft a brief, concise email asking the following:
1. Can you confirm that the final number of grafts totaled 3,501, and that the area of the strip removed was 24.52 cm sq.?
2. Can you confirm that in order for a strip of that size to yield that number of grafts, the original density must have been 142.7 grafts per cm. sq.? (# of total grafts / sq. cm. of strip removed = density)
3. Can you comment as to whether you have, in your practice, observed a density of over 140 grafts per sq. cm. from a donor area? If so, how unusual is that density?
The shorter and clearer you make your email, the better--reduces the possibility for them to avoid the central question (this is my lawyer training speaking). Use numbered questions or bullet points. You need them to acknowledge that you had a donor density of > 140 sq. cm., and then to comment on whether that is possible.