BES, Outlook Calender, and Cached mode

[seamonkey420]

i have a blackberry user that has had this happen to a few appts in
his outlook.

here is my situation:

i have a user w/a Blackberry Pearl that we use BES to sync his
outlook's email, calender, tasks, notes, and contacts to his Exchange
account. We are running Outlook 2003 and i believe his outlook is
setup to use Cached Exchange mode.

we are running the most recent patches (or those required by Exchange
and BES to be DST compliant).

our user had an appt that was created in outlook and showed up fine.
it then was synced to his blackberry. however the next day he went to
his outlook and did not see it show but still saw it on his
blackberry.

is this a case of being cached exchange mode and outlook not updating
the server w/the calender but yet the BES server was still able to
send it to the device?

any ideas?

thanks