Hi Kathy and welcome to this forum .....
So glad you posted your situation to get some feedback from others in similar situations.
Although I did not have the same situation you did, I did experience regrowth of my AN after my first surgery, which was retrosigmoid approach and no radiation following it. In my case, radiation is not a good option for treatment because of exposure to high dose radiation in my early teen years. Therefore, I had a second surgery in May, 2011 (via translab approach) 3 1/2 years after the original surgery. As of my most recent MRI (November, 2012), a smidgen of something is still being watched. I pray it does not grow again or I will be faced with yet another treatment decision.
I pray that your tumor is not growing. Sometimes it can appear to grow/change when it is just a difference in MRI machines and/or different radiologists measuring. The margin of error is 1-2mm so that needs to be factored in, as well.
Let us know how you are doing.
Clarice