No, you don't need to carry a license for stump shooting. But, I wouldn't carry any broadheads either. I've met some field officers while stumpin' without any problems, just good conversations.
As usual, you do need to be up on regulations. For instance, it's illegal to shoot a bow on Boulder Open Space, some of which looks like prime stump shooting grounds to an archer (regulations that some are pushing to extend to national forest land). But, these spaces tend to be posted at likely entry points.