Is the presence of these joint sounds serious?

Probably not. Since i'm not there to hear them and are not described i assume it is a crunchy scrapy sound. This sound is called crepitus and is very common with arthritis. It is a harmless noise and has no correlation with disease (arthritis) activity or stage.
Not normal. Any unusual sounds such as grinding, clicking or popping are abnormal and are the signs of some damage to either the cartilage, the disk or the bone . Some patients can have pain as well as sounds, but the absence of pain does not mean it is ok, you need to have a consultation with as specialist to determine what sounds you are describing and what to do about it, and sometimes nothing.