Normal or not

The past few days I noticed when my daughter nurses my breast gets really warm. But only while she is nursing and after letdown. Is this just the milk flowing? Hadn't really noticed before but we've been going so much here lately and running around trying to move that I'm not sitting to feed and started to notice. Yesterday it did feel like I had a plugged duct but I massaged my breast while she nursed and it eased out and doesn't feel like that today.