She was not looking at him while she described him; "that man over there is x in height"
She was trying to bring back to mind a vague memory she had of someone she had briefly seen, at some point, days earlier.
As has been pointed out, people don't have photographic memories, they are notoriously unreliable in describing someone they had no particular reason to particularly notice, much less scrutinize.
I certain don't walk past everyone I encounter on a walk and mutter to myself "5'6, navy blue jacket, is that a hat he's wearing or is his hair curly?
JMO