Chin pairing: sleeping next to new chin's cage?

So I'm currently attempting to pair my 2 year old male with a 3 month old male using the side-by-side cage method. Their cages are currently about 4 inches apart. Since starting this side-by-side method, the older boy has been sleeping right up next to the bars of his the cage on the side of the new little one's cage. His eyes are closed when he sleeps, sometimes angled away from the little one's cage. I feel like these gestures are trustful, but I've also read that chinchillas in the side-by-side method like to "protect" their cage by staying on the side that the other's is close to; however, he's literally just sleeping... with his eyes closed. Could this still be his defense (vigilance?) or could it be a good sign for the pairing? He just looks so relaxed.

EDIT: And he doesn't usually sleep in that space; he started when we started the pairing process.