Hey, aww don't worry about it, it's only natrual for him to say that, he's been living out for a while, but it probably just slipped out, and probably didn't say it consciously. I'm sure he still regards your house as 'home'. He probably see's uni as his second home maybe? How often does he come home?
I can kind of relate to you, my older bro moved out for uni in sept. But he comes home every week, and so it doesn't seem as though he's really gone. I think he might of referred to uni as 'home' by accident as well, which I can understand he spends more time there, but he still see's this as his home.