Is this an side effect of Plan B?

Jerika

Hey y'all can someone please answer this my period ended on July 17th, I had unprotected sex on the July 21st and took Plan B on July 23rd. On. The 31st I noticed slight spotting that was bright red and after a few hours it was brownish red and now it's gone. My next period is supposed to start on August 10th. Is this a side effect of the morning after pill?