It's only expected. Currently, I am reading a book called "Breaking into the game industry" by Ernest Adams, and I read a section about legal rights and so on. Basically, the employee signs a contract and all their work belongs to the company.
The funny thing is that at the time when they are working at the company, they can't make any games of their own if they use the company's facilities, code, and so on.
Interesting read, if you want to work on video games (like me
