A long time ago I was teaching my dog to pause at street corners, until given permission to cross. I thought I did a pretty good job - until I realized I had fallen into a common training trap.
I hadn't actually taught him to wait for the release but did train him to wait about 4 seconds before crossing :)
Humans fall into patterns of behaviour very quickly and easily. I had fallen into a pattern of waiting for a specific amount of  time without realizing it.  My dog sure knew though!  One day I decided to test it.
I began by not saying anything. Sure enough, at the 4 second mark, my dog would go to cross each time.
What an eye opener that was!
I began to retrain by pausing for varying times at the each corner before releasing to cross. I wanted to make it clear to my dog it was my release to cross not a specific time frame.
It was not easy to change my behaviour pattern! I had to make a deliberate effort each time to ensure I didn't fall back into that trap.
The same thing can happen with the food bowl. Is your dog actually waiting until you've said "okay" or....... have you taught him that you say "okay" at the 3 second mark?
Something to ponder :)
Do a training check the next time you are with your dog.