This sounds like one of two things:
A-There is some "bad blood" between Iowa/Stephens & the D.A. is going overboard in trying to prove a point.
B-He was arrested on an out of state warrant. If this was a felony warrant & Iowa requested his extradition, he would be held without bail till he is extradited.
Seeing as Iowa requested Minnesota authorities to arrest him, scenario B sounds like the more likely scenario. They knew where he would be.