You're observant! The nose is definitely a weak spot when drawing. There is definitely more shadow where the nose meets the upper lip area- I avoid putting it in sometimes (and definitely avoided it today) for fear of making the bottom curve of the nose looking like one big nostril! What I could have done is use a fine ink pen (or the very tip of the marker I was using) to get that shadow in.

I also find it hard to get lines/shadow down when using ink (e.g., smile lines, lines around the nose, eyebrow furrow, bags under the eyes) because I keep feeling it makes the person look more haggard than they are. Sounds silly; I still haven't figured out how to resolve this yet.

If you do find it, your self-portrait would be really helpful. =)