My daughter had her first period about two weeks ago. there was incredibly light bleeding that lasted 15 minutes for two days. should i be concerned?

No: Menses at the beginning of menstruation are often variable and may be light or heavy and may be very irregular due to inconsistent ovulation at the beginning.

Common: First cycles are often a bit odd as most young women will not ovulate ( release an egg) & form the hormone which stops the flow.Irregular timing, weeks to months between cycles is common. Light flow for several days or heavy flow could also occur. A call to your dr's office to discuss your child's situation is reasonable if you find it worrisome.