MySQL id not saving in order (Laravel in production)

I'm really confused about this.. So, I created a Laravel app and hosted it on Heroku. I'm using ClearDB extension to be able to use MySQL. Problem is: when I save a new User on my DB, it is not being saved in ID order. I got id 1, then id 11 for the second register, then id 21 for the third... Then I deleted them and tried again, and I got id 31. I think, there's a pattern, huh? It's going +10, +10... But why? Look, the code I'm using to save a new register is only: DB::table('registers')->insert($registerData); On the $registerData variable, I have only the following data: name, e-mail, a url for the picture and birth date. Even my "migrations" table is in this order: 1, 11, 21, 31...