why did albert pass sacret remark when lilly saved his life?

Lilly actually doesn't save his life. In chapter eleven, it is then end of July. One day, Lily takes a blanket to the beach and settles in to eat the supper Gram prepares for her. Suddenly, Lily sees someone thrashing about in the waves. Lily discovers that Albert is trying to teach himself how to swim. This annoys Lily, who would like to eat her meal in peace. Convinced that the boy will drown, Lily jumps into the water in an attempt to save Albert. When she is unable to reach the boy, Lily manages to make it back to her blanket. Albert joins her shortly thereafter. Lily explains to Albert how sometimes at night, she sees military ships on their way to Europe to fight the Nazis.