In the opening pages, why is David angry at Christopher, April, and Jalil?

At the start of Discover the Destroyer, David is outraged that Christopher, April, and Jalil distrust him: "How many times had I come through for them, for us all? How many times had I stood out from, not alone maybe but out on the line, out at the point where danger pressed closest?" This is part of a long rant about what he has managed to accomplish in Everworld, and he is hurt that he is distrusted.