It wouldn't let me enter a user-name with capitals (One at the beginning, one in the middle). Not sure if this is a design or a validation problem, but if it's

It wouldn't let me enter a user-name with capitals (One at the beginning, one in the middle). Not sure if this is a design or a validation problem, but if it's all lower-case by design, just do that once you've gotten my username - don't force me to sit there scratching my head. The validation hint said it must contain only 'letters, numbers, and -'. Nothing there about capitals.