Wouldn't be much of a gift if I were expecting something back, though I understand if you feel a little compelled to make things even with me. A lot of people do.

[Thus showing his hand a little too much, and thereby revealing that he does, in fact, just. Go around giving bottles of nectar to everyone, apparently.]

If you need a reason for it, consider it a "Welcome to the Underworld, appreciate you being kind to my dog" sort of thing.