I may be having a senior moment, but I don't remember saying "under God" in the Pledge of Allegiance in grade school before World War II. Didn't President Truman add that to the pledge?
Your memory isn't faltering. The word "God" wasn't in the original pledge written in 1892 and adopted by Congress 50 years later as a wartime patriotic tribute. Congress inserted the "under God" phrase in 1954, during the Dwight Eisenhower presidency.