Does the ZA Lynx boss have a hidden threat mechanic?

I understand all the ZA fights. But during the Lynx boss when the Spirit of the Lynx comes out it seems like healers get extremely high threat against it.I was off tanking on my paladin and my job on that fight is to grab the Lynx when it appears. I have down consecrate and immediately Judge Righteousness on the Lynx but it still goes to a healer. Then I taunt it and continue building threat but it still breaks off to a healer.According to Details! the healer had 22,000 threat in just a few seconds! So it was impossible for me to get it back. Luckily he healed through it and we got the bear mount.So anyways what is the deal with this fight? Is there some weird threat mechanic that I'm not aware of?