Derp – I say ‘New Updates made Today’ but actually should say ‘Made recently (which I installed today)’.
One other thing I noticed, that shouldn’t be causing any issues but is just a matter of best practices, is the use of wp_print_styles to output the datepicker css on line 86. The Codex reports this as a deprecated function now, but I’m not immediately sure of whether just wp_enqueue_styles can be left as a drop in replacement or more is required.
Thanks very much for the super quick response too!