Recently active topics in I want Sandy tagged with reminder time allday

In Settings / Date & Times, I had the

Default reminder time

When should I remind you about all-day events?

set to 6am.

I just got an e-mail (at 8pm) saying:

A friendly reminder about:

#1 Water soak the two orchids
- Email and Twitter reminders at 8:00pm

I don't need to point out that 6am != 8pm. My timezone is set to America/Los Angeles.

Sandy, you're going back to secretary school.

Am I doing something wrong? Any ideas why this is not behaving like I expected it to?

Thanks,
Graham