Should you bleed after Plan B?

Ana

Hi everyone, I took the plan B pill yesterday afternoon, and this morning around 6 AM I noticed some very light red spotting when I went to wipe, however by 8 AM it went away. I’m on day 28 of my 30-32 day cycle. I heard that you’re supposed to bleed after taking plan B, and if you don’t it’s not a good sign. Is this true? Thanks for the help.