It's normal for dogs to seek something to lie in or under. It's denning instinct and part of why crate training is easy for many dogs. (And why outdoor dogs don't generally even require training to use their houses) That said, if this is a new it could be a sign of something. Fear is a common reason - but if this behavior is constant and doesn't just occur when something happens that might scare her (a thunderstorm, an argument between two people in your home, or hearing the word "bath" [all things that cause some of my dogs to "den up"]), then I'm willing to bet that isn't it. It could very well be the heat, as well. When it's hot, my dogs tend to lie under furniture. Tables, chairs, beds... However, it wouldn't hurt for you to ask your vet so you can rule out health problems. My Corgi mix hides a lot but generally, seeks said shelter in her crate. A while back, she started turning to hiding under my bed and in the corner in our living room, under our end table. I didn't think anything of it because I assumed it was the same as being in her crate. A week later, her "area" was swollen pretty badly. I rushed her to the vet and she had an infection. Nothing too serious, it was cleared up with antibiotics and pain killers. But the hiding probably was a result of her being sick. Keep an eye on her for other symptoms, just in case.