Its no problem. Back in 2011, he had sudden kidney failiure. Healthy all his life (he was born in our house so we had him since before he was born). He was gone within less then a week from the first signs.
you know what's weird? the exact same thing happened to me. I had a cat named Genie, and she died in the middle of the night in my bed... Now, I have Binoo and Anastasia, and they keep me happy just like Genie did!