[jellybean]

...on rereading your post I wonder if the error does not arise instead from Obama's poor sentence structure.

Poor sentence structure doesn't explain how they watched the Watergate hearings every night on TV in 1972.

The legend is his father visited Hawaii when he was 10 (Christmas 1971). It doesn't make sense to refer to his father's visit as occuring "before my eleventh birthday". Either way, "the summer after my father's visit to Hawaii," would still be 1972 and "before my eleventh birthday" would also be 1972.

[wideminded]

I was thinking that perhaps the father visited just before Obama’s eleventh birthday, in other words in 1972. But you are right; the photos of them together in the airport clearly show Christmas trees.