Lion from the app store asking for random login details!

Hi i have a 2011 Mac Air 11"

Today i did a reinstall of osx lion. I erased the disk and connected the internet to reinstall, everything went fine no problems but when i went to the Mac App Store in the Purchased section, it showed Lion there with "UPDATE" instead of installed. When i click update its saying i need to sign in with some ramdom login details not my own! I thought when that happened it means its a cracked app isn`t it? How can that be?

My Mac came with lion on it, i also bought another copy of Lion in my account.

Anyone have any ideas? should i contact Apple?

thanks

Kaato.