Heh, they hadn't at the time, but yes, they did. They still haven't answered a couple questions... like there's a whole timing issue around divine challenge, when the damage applies, when the heal triggers, whether forceful challenge lets you move people out of melee before they hit, etc.
If the heal triggers after the attack, it means that it's near impossible to kill an ally of the hospitaler's through his mark (ie, cause even if reduced to -50, they'll heal 10 and be back at 10hp)... if it triggers before the attack (like many assume divine challenge does), then you might not have anything to heal. Kinda lose either way, really. I wish it just reduced damage by that amount instead. But eh.