After another player plays a or card, you gain from the matching favor bank.
Standard DeckHearthSearch FAQ
Q: When exactly do I gain the favor?
A: Immediately after resolving the text in the relevant 5.1.4 subsection. So they gain favor for playing to site first, for example, but resolve When Played powers (7.3.3) after Saddle Makers.
or 
card, you gain 