Hay, at 38 weeks yan talaga normal na, ang light brown discharge na ganyan ay usually just the mucus plug starting to loosen or old blood mixed in, nothing to worry about! A few of us moms experienced the same thing weeks before labor, kaya just keep an eye on it, if it becomes heavy bleeding or super red, that's when you should call your OB agad, pero from what you're describing sounds like your body's just preparing na.