A new chinchilla should be kept in a cage in a separate room for at least 30 days quarantine before allowing him to be caged in the same room or interact with other chins. A new chin may appear fine but could be harboring an illness. Also, quarantine is done to allow a chinchilla to adjust to a new environment and to allow their intestinal bacteria to normalize from the stress and change in diet. It is already too late now but hopefully he has adjusted well and is not stressed or ill. Just keep that in mind if you adopt another chinchilla.
Chins make a lot of noises and they're a bit hard to describe. If I'm thinking of the correct chortling sound (kind of sounds like multiple rapid laughing noises), I often hear it when I enter a room too abruptly or do something loud/quick that scares the chins. They often make this sound after a dash to the other side of the cage into hiding.
Otherwise, if it's the noise that sounds like the quick laughing noises followed by a few longer and deeper notes at the end, I interpret that as a kind of inquisitive yet kind of forlorn communication sound.
All this is just speculation, but that's my interpretation of the sounds, although I'm not sure if it's the same sound you're hearing, lol.
