If this is before the cataclysm the stranger thing might be the date rather than the name.
Also the name he gives is also the old lady death magician at the temple that fills in for Claude when he's in a coma so it's not just a random name he came up with on the spot. Childhood Claude is also drawn with freckles.
well, he literally saw an unknown calendar system, and that she was born 23 years starting this... and if it was not enough to understand she came from the future, she gave him some infos about an older priest-version of himself...