My Guinea Pig is acting a little strange?!?

I am completely 100% sure of this because I have had 5 guinea pigs so far and every book and Internet article that I've read says: If you notice your guinea pig lying on their side, it's usually because they are relaxed and comfortable. Bottom line, they're just chilling out. Don't get worried because my guinea pig always does this and she never gave birth or gotten seriously sick after doing this.