Sometimes radiology reports sound very scary. The radiologists don't know your individual history particularly well, and tend to make a big deal out of normal post-op findings. My 3 month post-op radiologist report also made a big deal of some enhancement, causing compression etc. However the written report that I got from my neurosurgeon stated that these enhancements are normal post-operatively and that he was actually "very pleased" with the excellent appearance. Like your surgeon, he recommended follow up in one year (as opposed to 6 months follow up recommended by the radiologist). Even though the radiology report had me worried, I decided to trust what my neurosurgeon said, since he knows best.
All I am trying to say is that sometimes the radiologists try to be overly cautions (rightfully so), but they are not always aware of the particular situation. It seems that your neurosurgeon is not concerned either, otherwise he would have recommended follow up sooner. You might want to send him the radiologist report, and ask him to clarify more on these findings.
Marianna