That's a problem with PayPal, not Gmail. You can't register "myemail" if someone else has already registered "my.email", so PayPal must not have verified the address (unless you accidentally clicked the verification link yourself).

There was an article posted recently that complained about how Netflix lets people create multiple accounts using dot variations of the same Gmail address, and plenty of people pointed out how it made no sense to blame Gmail for Netflix failing to verify email addresses: https://news.ycombinator.com/item?id=16781959