Word of Healing and Divine Boon

The Word of Healing skill adds extra healing power when the target other Ally is below 50%. However, I have noticed that with Divine Boon on, which heals my ally whenever I cast a spell on them, I do NOT receive the added bonus from Word of Healing when ally is below 50%, unless they are really low on health. It seems to me the game is adding the divine boon healing bonus, then checking if your target ally is below 50% to calculate the correct healing power of Word of Healing. Is it suppose to work this way, and is anyone else noticing this?