BuddyPress.org

I can confirm the problem. The issue occurs if you have a negative GMT offset. Since xprofile dates are saved for midnight of the chosen day, anyone with a negative GMT offset will have their date shifted backwards, which then displays as the day previous to the one chosen.

ie –
Date Chosen: January 4th, 2011
Saved in Database as : January 4th, 2011 at 12:00am GMT
Timezone: Central Standard Time (-0600 GMT)
After bp_format_time(): January 3rd, 2011 at 6:00pm CST

I’ve added a patch to https://trac.buddypress.org/ticket/2779 to fix the issue.