I don't do that. To be honest, I would probably be a little taken aback if I got a convo from a seller if I favorited their item.
I send thank you's to customers, both via convo and with a thank you card when I I ship their items, and I will reply on FB when someone says something nice about an item I posted there. But not for liking my shop or an item of mine.
jmo, there may be people who do that same as you. It would just be uncomfortable and not 'me' to do that.