Have you had any vigorous sex yet? Def not pregnant?
It could be a whole host of things, 99% of them nothing to be concerned about. Cervical erosion, vigorous sex, ovulation bleeding etc. Even constipation can cause occasional vaginal bleeding due to pressure exerted on the vaginal wall/cervix.
Keep an eye out today to see what happens just to make sure it doesn't get heavier. I'd see a GP when you get back for peace of mind and to get it noted but the general advice I got when it happened to me was to leave it and see if it happened again. It turned out I was pregnant actually and had a small erosion but at the time the advice was to wait and see.
Have you recently stopped taking any hormonal contraceptives?
Aah, you're taking a new hormonal contraceptive and have new irregular bleeding? It's listed as one of the side effects of starting a new pill and it sometimes just takes a while to settle. I was always warned that it was more likely on a low dosage pill.
As show indicated, when you wipe is not likely to be a huge cause for concern. As you come off the pill your body gets a bit confused at having to manage it's own hormones. So to be clear you're thinking you're cd9 - did you bleed like a normal period when you stopped taking the pill?