AHA! I now believe it is a balance issue, but not rolling too much. I watched this video last night:
and tried this morning to pay attention to my lead hand, patient catch. My right arm stays extended as my left arm recovers. However, when I spear with the left arm and rotate to breathe (I breathe right side exclusively for the time being), my left arm sinks and begins the pull a bit too early. So I guess I need to do a lot of skating drills with rotating to air--which I have found quite difficult. Need patience with myself in addition to the patient lead hand!