The Past Two Days I Have Been Experiencing Light, Brownish-pink

The past two days I have been experiencing light, brownish-pink spotting. My period is not expected for another 4 days, and my cycles are very regular. I've never had spotting or bleeding outside of my periods. I had sex this morning, and afterward there was more blood, but still not enough to warrant wearing a pad or anything. I have not had anymore bleeding since then.