Events repeated every day always skips the first week of the month

I added an event to our Calendar node (uses the date api) that runs from January thru April. Everything displays OK except the first week of Feb, March and April. The events are not displayed in the calendar.

Upon debugging, I found my way into _date_repeat_calc() in date/date_repeat/date_repeat_calc.inc which is I think responsible for determining which days match the requested rule.

RRULE:
FREQ=DAILY;INTERVAL=1;BYDAY=SU,MO,TU,WE,TH,FR,SA;UNTIL=20100418T160000Z;WKST=SU

Returned $days by _date_repeat_calc():
[9] => 2010-01-28 00:00:00
[10] => 2010-01-29 00:00:00
[11] => 2010-01-30 00:00:00
[12] => 2010-01-31 00:00:00
... NO DATE from Feb 1 - Feb 6 ...
[13] => 2010-02-07 00:00:00
[14] => 2010-02-08 00:00:00
[15] => 2010-02-09 00:00:00

[33] => 2010-02-27 00:00:00
[34] => 2010-02-28 00:00:00
... AGAIN, MISSING DATES HERE...
[35] => 2010-03-07 00:00:00
[36] => 2010-03-08 00:00:00

[58] => 2010-03-30 00:00:00
[59] => 2010-03-31 00:00:00
... AND AGAIN ...
[60] => 2010-04-04 00:00:00
[61] => 2010-04-05 00:00:00

Using the dev version, I found this line that excludes those dates (line 291-293, date/date_repeat/date_repeat_calc.inc)

if ($rrule['FREQ'] == 'WEEKLY' || date_format($current_day, $format) == $current_period) {
  date_repeat_add_dates($days, $current_day, $start_date, $end_date, $exceptions, $rrule);
}

The last week of January starts at 31 so that period looks like this
01-31 - Sunday
02-01 - Monday
02-02 - Tuesday
02-03 - Wednesday
02-04 - Thursday
02-05 - Friday
02-06 - Saturday

The line 291 above checks if the current day's month is the same of the current period's month which will return false. Disabling this condition resolves my problem of missing dates.

The question is, what was the reason behind line 291? Disabling this might resolve my problem but could cause another problem in other rrule so I want to understand.