Am I being over prescribed?

I am so grateful to have found this site. It appears to be just what I was looking for.

I'm a very athletic 66 year old male with an uneventful health history except the normal aches and pains of aging. I play basketball in a senior's league 3 times a week and walk 3 miles a day, 3 times a week. I have never taken prescription medications for anything other than antibiotics for colds etc. I have annual physical examinations, and I recently completed a stress test which was reported as excellent, (as were all my previous ones). I am insured by a HMO medical plan.

I was recently diagnosed (by accident) with having a non symptomatic, completley occluded, interior carotid artery. I was referred to a vascular surgeon who ordered a MRI/MRA, and the results were extremely positive; as the blood flow was being rerouted around the blockage. The other carotid arteries and branches were unremarkable, and had a negligible amount of cholesterol blockage (<20%) which I was told is less than normal for my age. Although there was no conclusive evidence as to what actually caused the carotid artery blockage, The Dr. told me that no further tests were warranted since my condition was non symptomatic with an excellent prognosis. He also stated that further testing most likely would not be approved by my insurance carrier because of this.

I was told that this condition is not correctable by surgery, nor treatable by any medication. The blood flow to my head continues uninterrupted through collateral arteries that have rerouted themselves around the blockage. There were no peripheral or collateral damages noted in my tests. My prognosis from this doctor is to follow a healthy diet, continue to monitor my cholesterol and have an annual follow up to check my other carotid arteries. No lifestyle changes are necessary, and I can continue my current daily regime uninterrupted, including my exercises.

After returning to my GP, I was prescribed 5mg of Lisinapril daily for BP control and 20mg of Simvastatin (generic for Zocor) for cholesterol as a precaution.

I take and log my BP twice daily. It has averaged 118/75 a month and my pulse averages 60. My BP recently spiked a few times to as much as 147/89 but I attribute that to going through the carotid artery thing. From everything I've read, I don't think I have high blood pressure.

Also, my 5 most recent blood test results since 10/06 are as follows:

Total cholesterol count has averaged 212 with a high of 254 and a low of 186 (recent results are trending lower). My LDL has averaged 119 with a high of 139 and a low of 105 (They're also trending lower).

I am concerned that I am being over prescribed by my GP, especially with the 20mg of Simvastatin. According to the chart, when comparing my worst cholesterol reading of 139, I should be taking a dose of 10mg of Simvastatin (for readings in the 126 to 159 range) With my last three LDL readings of 114, 109, 105, I would assume that I would fall into the 101 to 125 range which calls for only a 5 mg dosage on the chart.