Self conscious bf

My bf is like super hot and muscular and just amazing. We will have just finished having sex and one of us usually goes to get water or juice or whatever and once he went to get some water and I went shortly after and he freaked at me saying not to look and how he was naked! I don't understand how he can freak out about that tho! He's so handsome and muscular and in shape and I tell him how beautiful and attractive he is all the time! And it's not like we didn't just finish having sex and I didn't just see him naked!