should I be concerned

So I'm close to 5 weeks and when I got back from taking my trash out (a little heavy fiancé said he would but I was already in the process lol) and cleaning etc I came inside to use the bathroom and had some brown in my undies..it has me a little nervous. Should I be? Or is it kind of normal? Never noticed with my other pregnancies my girls are 6&4 so it's been a while. Anything helps. T.I.A☺️