Hi! So far I don't have any yellow issues or signal issues but my screen seems pretty dark in a low light situation when the auto-brightness is set "on". I have the same setting as I had with my 3G but the iPhone 4 seems much darker in low light. When I put it under ample amount of light, the screen is bright and if I turn off "auto-brightness" the screen is pretty bright as well. When auto-brightness is on, is it normal that the screen is dark in a low light situation?