Unexpected colour in the cafe

After a day of heavy drinking at a friend's wedding, we decided a nice breakfast was in order.

We went to a local cafe that had just opened for iced coffee and a warm baguette.

While waiting for our order I noticed that every time I moved my head, the knife and fork on the table in front of me kept flashing with colour.
There was a neon sign on the wall next to us that was reflecting onto the surface of the knife that make it look like light reflecting off an oil slick on water.

Bringing my phone to eye level I was able to replicate and snap a photo of what I was seeing before eating my food and going home to sleep off the rest of the hangover.