Is This Normal To Have Brown Spotting After Oral Sex?

I took plan b two weeks ago today. My bf and I performed oral sex on each other. After orgasmed, and cleaned up, we kinda fooled around the I think he inserted his fingers into my vagina (can't remember). I was worried I could get pregnant that way. I'm not on any birth control. Took it within 24 hours. Today I have light brown spotting. Is this normal?I am 31, weigh 128 and an 5'4