"But how on earth did you get past the goblins?!" Kili asked, astounded that the hobbit had managed to escape the tunnels alone.
"How indeed!" Dwalin echoed, wanting to know just as badly.
"Yes, well..." Bilbo cleared his throat awkwardly and slipped the ring subtly back into his pocket, hoping they wouldn't notice.

Gandalf however it seemed had noticed, though he didn't say anything and simply shook his head. 
"That doesn't matter now, what matters is he is back, and all in one piece!"
"It matters!" Thorin insisted in a growl, stepping forward. "I want to know!" turning to face the hobbit he asked. "Why did you come back?"