Here is the email i got back after asking account services.

Greetings,

This is actually perfectly fine. Mike is a very common nickname for Michael and it should not provide you with any issues as far as account ownership goes. It is when a user puts a fake name on the account when we run into a problem(like Cheeseman Rocks... lol). Please let me know if you have any further questions or concerns!

Lance P.
Billing and Account Services
Blizzard Entertainment
www.worldofwarcraft.com