I'm noticing yellowing in his skin. Is this a symptom of old age?

I haven't been spending as much time with my boyfriends dad(who has dementia) lately, as I have been very busy. Yesterday was the first time in a couple weeks where I was very up close to his face. I noticed that his face has a few spots of yellowish tint. his last doctor's visit was a month ago... I'm wondering if this is something we need to bring to the doctors attention? Or is this just a normal symptom of old age?