Mysql rollup issue when grouping with quarter and date - mysql

Question

I have this simple query:
select quarter(invitation_date) as `iQuarter`, invitation_date as `iDate`,count(*) as count from data group by iQuarter,iDate with rollup
I would expect to get a table like this:
+----------+------------+-------+
| iQuarter | iDate | count |
+----------+------------+-------+
| 1 | 2010-02-23 | 133 |
| 1 | 2010-03-02 | 14 |
| 1 | 2010-03-09 | 74 |
| 1 | 2010-03-15 | 102 |
| 1 | 2010-03-22 | 76 |
| 1 | 2010-03-30 | 16 |
| NULL | NULL | 415 |
| 2 | 2010-04-06 | 20 |
| 2 | 2010-04-12 | 84 |
| 2 | 2010-04-19 | 85 |
| 2 | 2010-04-26 | 51 |
| 2 | 2010-05-03 | 73 |
| 2 | 2010-05-11 | 76 |
| 2 | 2010-05-18 | 54 |
| 2 | 2010-05-24 | 83 |
| 2 | 2010-06-01 | 73 |
| 2 | 2010-06-07 | 74 |
| 2 | 2010-06-24 | 81 |
| 2 | 2010-06-28 | 110 |
| NULL | NULL | 864 |
+----------+------------+-------+
But what I get has the total in the wrong position and before every quarters total we have a row with the next quarter with a count of one.
+----------+------------+-------+
| iQuarter | iDate | count |
+----------+------------+-------+
| 1 | 2010-02-23 | 1 |
| NULL | NULL | 1 |
| 1 | 2010-02-23 | 132 |
| 1 | 2010-03-02 | 14 |
| 1 | 2010-03-09 | 74 |
| 1 | 2010-03-15 | 102 |
| 1 | 2010-03-22 | 76 |
| 1 | 2010-03-30 | 16 |
| 2 | 2010-04-06 | 1 |
| NULL | NULL | 415 |
| 2 | 2010-04-06 | 19 |
| 2 | 2010-04-12 | 84 |
| 2 | 2010-04-19 | 85 |
| 2 | 2010-04-26 | 51 |
| 2 | 2010-05-03 | 73 |
| 2 | 2010-05-11 | 76 |
| 2 | 2010-05-18 | 54 |
| 2 | 2010-05-24 | 83 |
| 2 | 2010-06-01 | 73 |
| 2 | 2010-06-07 | 74 |
| 2 | 2010-06-24 | 81 |
| 2 | 2010-06-28 | 110 |
| 3 | 2010-07-06 | 1 |
| NULL | NULL | 864 |
+----------+------------+-------+
Invitation date is defined as:
+-------------------+---------------------------+------+-----+---------------------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------------+---------------------------+------+-----+---------------------+-------+
| invitation_date | date | NO | | | |
+-------------------+---------------------------+------+-----+---------------------+-------+
Anyone have a clue on why this is happening? Mysql version: 5.0.27