I had this happen to me recently. One of our cats got out in the morning. Our other cats never leave the back yard, even when left out all day. I figured this one was no different, so I said screw it and left him out there. Hours later, I forgot I had left him out, so I went out there expecting to find him hanging out in the back yard. Nope. He was gone.
I wandered the neighborhood calling his name for 4 hours… up and down every street several times. I peeked into as many back yards as I could, calling his name. I sat in my back yard and called his name over and over. Nothing.
My wife was pissed and we were both sad. We went to make lost signs to post around.
Just before starting to post the signs, we went to check the back yard one more time. He was just sitting there as if nothing had happened. He was a little dirty with some cobwebs, so he must have been hanging out under the neighbor’s house. He probably heard me calling his name and decided to ignore me because his little adventure was more interesting.
Hope it turns out for you. Hopefully, he is on a little adventure, gets hungry, and comes home.