Answer:
The white scab is called secondary healing. Pretty much, it is a brand new layer of sking growing over the top of the tattoo. Because the skin is fresh and an irregular pattern to it, it will look a little funny. Do not stress about it. If you give it about a week, that layer will peel off, and under it you will have a shiny layer over the tattoo. Give that a week, and you will be fully healed up.
From the sounds of it, your tattoo is healing great, but if you have any further questions, you should go to the shop where you got the tattoo to have them look at it. It is really hard to make a call on how the tattoo is healing without being able to see it.