edit: Wait, you were notified during registration of the trademark infringement, but were allowed to register anyway?
Its pretty common for the registrar to do an auto lookup to see if you are registering something similar to something that already exists.
Example, live in a city called Mt Vernon. Registered a domain name that started out www.mtv-xyz.com. Was notified that it could possibly violate MTV trademark. Let me register anyway, and of course I have never heard anything from MTV about it because it doesn't relate to them at all.