Mantra of Solace used with Healer's Retribution not providing retaliation on 2nd and 3rd charge use

I noticed tonight that when I used the FB heal skill Mantra of Solace with Healers Retribution traited, I received retaliation on the first use of the heal, but not for the subsequent second or third charge. Has anyone else seen this? Is this a feature or a bug? Thanks!

Healer's Retribution has a 20s cooldown, are you sure it wasn't that?

Ah, you are right! I didn't notice the CD on Healer's Retribution. Mystery solved!