fed stool color?

My daughter is 7.5 weeks and for a few weeks now her bm's aren't the watery yellow with curds. It's turned to a mustard consistency and is a dark yellow almost like dark mustard color. She is solely fed and has never had a drop of formula. I know this for a fact as I stay home with her and the two times she has been given a bottle was by my husband who fed her expressed milk and wouldn't give her formula in a million years without discussing this with me first. She acts normal has several good sized bm's a day, plenty of wets. Goes about 3 hours during the day between feedings. Then probably nurses every hour in the evening time. Then uses me as her pacifier all night long. Any ideas what this could be? or should I even be concerned? I don't remember my two older girls bm's turning into this. Thanks so much