Little bit of Breakthrough Bleeding?

I'm on the combined pill and this month during week 2 of my active pills, I randomly got a little spot of blood. It stopped within minutes though. I haven't had breakthrough bleeding since I was first adjusting to the pill so this kind of worried me. I know I'm probably not pregnant because the last time I had sex was two months ago and we used condoms along with my pill and I've had a couple periods since then. Besides that we only do oral and manual sex.