Can a baby sleep TOO much?

I know that there will probably be people who say, "count your blessings," but I just want to check what's normal. My son is 2 1/2 months old. For the last four days he has been super sleepy. He has been sleeping through the night for two weeks now but in addition, he has been sleeping a lot during the day. It kind of feels like just after he was born, when he slept a ton. When he is awake, he is happy, alert, very smiley, and chatty (in as much as a baby can chat!) I guess my question is, could something be wrong? Or is it just me being an overanxious first time Mommy? Last Saturday, we took him shopping and between 10 and 4 he was awake for only one hour. Then, when we went out to dinner three hours later, he slept through that too. Then he slept through the night. I'd appreciate any responses! Thanks!