Hi. My cat is an indoor/outdoor cat. Most of the time he is indoors but sometimes he wants to go out at night so I let him. Every once in a great while (if he has been indoors a long time) he will be acting friendly, then will scratch or bite, then he runs away from me. He is usually very friendly and is always purring when you pet him. So it is alarming when he turns against me for a moment. This only happens every once in a while. Does anyone know why he would act like this?