What Does Losing Mucous Plug and Spotting at 38 Weeks Mean?

It's normal to have bloody show as you start to dilate. Probably early labor. :) I did the same thing starting at 37 weeks 6 days and had my baby at 38 weeks 2 days

First labors usually take many hours. There are exceptions but if you just keep track of the signs and don't ignore them you should be fine.