Sleeping too much?

I'm not sure if I should be concerned. My daughter is 3 months old, she slept through the night for the first time last night. She slept from 10pm-6am, so 8 hours. Which was awesome. I fed her, changed her diaper and since it was 6am I laid her in the bed next to me. She fell asleep right away and now has been sleeping for an additional 3 hours. Is this much sleep normal? As the day goes on I'm curious to she if she will still nap.