6-8 mo old + 10 week old?

I have a cat that is 6-8 mos old, and we just got an 8-week-old kitten two weeks ago. The two cats have gotten used to each other and are getting along well. They play together most of the day and curl up and sleep together also, and seem to love each other by now.

My question is this: I noticed blood on the end of my older cat's nose and assumed it was probably a scratch from playing with the kitten. I don't know if this is a coincidence or not, but the day that I saw the blood on the end of her nose (you can clearly see a scratch, so I know the blood wasn't from INSIDE her nose), I noticed she had been sleeping most of the day. She's usually quite playful because she isn't very old, but I was wondering if it is just a coincidence and my cat is getting older and sleeping more often, or if there could be something wrong with her? Her behavior hasn't really changed at all, she's curled up in my lap, sleeping right now. I was just wondering your opinions on this, if the bloody scratch on the end of her nose might have anything to do with her sleeping most of the day?

She may just be playing harder, now with the company of a new kitten, and more worn out..just a thought.