I'm not sure if I'm BU. But if you take a present to a child's birthday, would you expect a thanks? From either the parent or the child. Being neighbours I've bumped into them several times since.
Went to a double birthday and get the feeling (something happened there where the type of item I had bought was being talked about in a dismissive way) they thought my presents were pikey (they weren't expensive, I didn't simply want to play that game of ridiculous presents for a child who was going to receive 30+ gifts, seems de trop)
I don't use facebook so unsure if a Group Thanks was sent out.