It could be nothing. Do you know where your placenta is? If it's low it may cause spotting, but pink wouldn't be such a big deal. Your cervix could have dilated a bit, but then it may stop and do nothing for 10 weeks.
Call your provider, they will tell you how worried they are in the context of your whole pregnancy. Likely, they'll have you in, listen to the heart rate and check for any ctx, and send you home!
Good luck to you!