SPOTTING PLAN B

On June 4th ( a Tuesday) I took plan b. Today is June 9th (a Sunday) and I started to spot a little bit. My period isn’t due for 2 weeks. I know plan b throws off your cycle and can cause spotting but 5 days seems like a decent amount of time for the plan b to be causing this spotting. Any ideas? I’ve taken it before and this never happened