Thank you for your question, Wendy.  Although blueberry plants can contract rust, a fungus, the red pistules are found underneath the leaves.  The redness in your plant's leaves is on top, and between the veins.  This is typically caused by a pH issue, which limits iron absorption.  https://pnwhandbooks.org/plantdisease/host-disease/blueberry-vaccinium-corymbosum-incorrect-soil-ph

I suggest that you get your soil around the bushes tested for pH and nutrients.  Here is the closest lab to do that:  https://al-labs-west.com/

I suggest that you contact them first, for soil collection techniques and costs, including recommended soil amendments.  Good luck!