In my humble opinion, it is rather a philosophic term. The philosophers have described four sublime states of mind, that include:
1. Love or Loving-kindness,
2. Compassion,
3. Sympathetic Joy, and
4. Equanimity
In a broad prospective, when we are grateful to someone, we may have some kind of compassion and love for one. So, prime fascia the use of this term, in your sentence seems to be alright. Anyways, I will also be grateful if some native speaker give some enlightenment.