In truth, the 8ight's throttle servo looks to be closer to the crank case than on any other chassis, what with everything being huddled closer to the centerline and all, so there may very well be a correlation between the two. The only other thing that I feel it could be would be stress put on the servo during hard braking, but as the system is very similar to what you see on other buggies, I don't think that's the culprit.
As for myself, I was planning to put insulation on the servo, the battery box, as well as the rear chassis brace so as to minimize any heat-related issues. Hopefully that will help somewhat.