Months ignored in Customize Default Value strtotime()

I created a CCK date field:

Widget: Textfield with date popup (also tried "select list")
Default value: Relative
Customize Default Value-> From date: 28 january last year
Granularity: Y/M/D (also tried Y/M/D/H/M/S)
Everything else is default

The default value is Feb 16 2009 (today's date a year ago). Date API appears to be ignoring my day and month.

I had similar results when entering "10 September 2000" (default value was Feb 16 2010).

The following PHP code returned "00:00:00 Wednesday, Jan 28 2009":

$time_string = "28 january last year";
echo strftime("%X %A, %b %e %Y", strtotime($time_string));

Thanks!