I wouldn't stress it unless it's become problematic in your life or has been going on for a long time... if it is/has, you might want to mention it to your gp.
I have times where my energy levels are lower and I can sleep 10 hours at night and still want a nap in the day.
But I am a person who requires a lot of sleep to function in general. 10 hours isn't too excessive for me or even far from my ideal. Things that make me more sleepy or make it harder for me to wake up... being sick, stressed, hormonal, dealing with a lot of stuff, the weather, lack of exercise, staying up too late, sleeping too much (I do hit a point where too much is too much), so on. It just happens sometimes. *shrugs*