LUD 4 days in a row

EB2, 485 has been filed for more than 8 months and changed job 6 monthes after 485 was filed (the same job category, applied H1B transfer, but i did not inform INS yet). my 2nd AP applicaiton has been approved on 03/15/07.

Since last wendesday (03/21), i found my online LUD had been updated everyday. Right now, the LUD is last Satursday 03/24/2007. However, my online status remain the same. Can people tell me what are the possible reasons for the consecutive LUD changes 4 days in a row?

Thanks.