Spotting while on the pill

I've been on the pill for a few years. I was lazy one day and took a pill from an old pack then the next day I took that days pill along with the previous days pill to stay on track (so I took an extra pill without skipping a day). I  noticed slight spotting a few days after my period ended (2 days after taking an extra pill). I went through the ovulation week and everything seemed normal. Today I spotted again but it was super faint. I haven't missed a pill at all this month so I'm wondering if the spotting could be from taking the extra pill or from friction or a cut.