I don't think it's an error - the preamble is too precise. I think the answer may well be to highlight the word you've pointed out - if that is highlighted, then it's 'seen', and if it's seen, then today (feb 2) is still exactly the same as feb 1- per defn 2 in Chambers- because it's still the same as the word highlighted which includes all the letters in 24a.
Does that make any sense?!