You bring up a great topic! And one that is dear to my heart.
Please see all the work we have put into this URL to try to help hams with grounding questions. http://www.arraysolutions.com/Products/ice/10.html
Also see this application notehttp://www.arraysolutions.com/Products/thorshammer.htm#top%20of%20page
Done by someone else.
What really is important is that your concerned and you recogize that you should do something, unlike most amateurs, until they get a $10,000 damage assesment caused by lightning. I write several of these each year for insurance claims.
Note that all arrestors are not alike. You need a static bleed choke in your arrestor. Stay away from the cheapies, and some of the more expensive ones, that do not have it. A gas discharge tube is not enouph.
Jay Terleski, WX0B