Up to what age is it normal for kids to see their parents naked?

My husband and I aren't nudists or anything, but we do sleep naked and so in the morning or at night sometimes we do walk around in the nude. My 6 yr old son has started making comments like "Mom, please put some clothes on." But I tell him if he has a problem with it then don't look. I don't feel like it's a big deal; if anything, I want my kids to grow up understanding that their bodies are nothing to be ashamed of. I tell them it's only ok for your family or the doctor to see you naked. We don't let the kids go outside nude or anything. And it's not like the whole family's hanging out on the couch watching tv together naked. It's just like, one of us gets up in the morning and goes in the kitchen to make coffee before getting dressed, or something like that. My daughter's only about to turn two, so she doesn't really have an opinion on the matter yet, but she did point to my husband's the other day and say "Ewww, !" which gave us a laugh. Anyways, I just wanted to get some one else's opinion.