I doubt a cat dug those, looks more like something a squirrel or large bird would do. Mice have clean, round exit holes......not the roughly dug holes in your photos.

If you do have a rat/mouse problem that may be why the cat is visiting every night. It is possible the cat was reaching into an existing hole trying to catch a mouse but very unlikely he dug a hole for the sake of digging a hole.

Here are some other marks I found on concrete that was only laid out few weeks ago. Who do you think made these?

My garden is potholed with those every morning. I use a shovel to level them out. It's probably either a 'possum, skunk, or raccoon looking for worms or other underground grubs. Cats don't leave holes, they use them and then cover.

I see Mickey Mouse and a tree and a beautiful woman and a jet plane... did I mention the other beautiful woman? (She's sitting right next to Mr. Rorshach!)