If a chinchilla is use to having other chins close by and/or sharing a cage with one, yes, they can get very moody ... then, sometimes, they just seem mad at the world for no reason ... even other chins ... but there is always a reason
you just have to find out what it is.
Jack, a standard gray of ours had been through two previous breeders and no one could figure out what it was he was not happy with. He would fuss and nip at us, but not hurt us ... he just seemed to want to be left alone.
We tried talking to him ... nothing.
We tried giving him time to adjust without intrusion ... nothing.
We tried treats and dust baths ... nothing.
We tried one-on-one time ... nothing.
We tried male cage mates ... still nothing.
We tried two different female mates ... he did not hurt them, but he would have nothing to do with them.
We tried a third female, Daisy, and it was like turning a light switch on ... he loved every body! We had finally found his true love for him.
They had several litters over the years, then, he passed away. We are now trying to find a mate for his mate he left behind ... she will have nothing to do with any of the males we have tried to introduce to her ... so far.
Sometimes you just have to continue to try different things to bring them around.
Jo Ann