i think your having breakthrough bleeding. i had this when i was on bc pills and my doctor had to change the precription. she said that my body had gotten used the pill and that was the reason for the breakthrough bleeding. thats what it sounds like is happening to you. talk to your doctor. hope i was of some help!
I wouldn't worry about this one particular time. If this starts happening every cycle, then definitely talk to your doctor. It might be time to change pills, like ashley said.
Thank you for the feedback. Now a dumb question: would this spotting be considered a period or not?
No, spotting is not your period. I suspect you'll get a regular period as usual, but that you're having this spotting now in addition to your normal period.