Your Goodall is absolutely perfect and exhibiting normal behavior. I know what you are seeing and feeling but it is completely normal and desirable to have this slight deformation. We have been building ‘world class’ instruments for over 35 years and we can not and will not build instruments without this slight deformation. It is not, I repeat, it is not an abnormal issue or an issue that will cause any trouble in the future.
We do not build our instruments too lightly and sacrifice structural strength but we also do not overbuild them to prevent this slight top deformation. Indeed some slight top deformation is entirely necessary for great tone production! There is about 160 lbs of tension exerted on the top from the strings so some top movement is absolutely normal. The wood is very strong and will tolerate this just fine. Please do not worry, or feel that your instrument may be exhibiting a problem.