If you text, you've probably gotten text spam. The messages often seem to come in the middle of the night, or in the wee hours of the morning, before the alarm buzzes to start the day. And the number of these annoyances has tripled in the last year -- to 45 million text spams a day, according to the security firm Cloudmark. One reason for the increase? More people are opening up messages on their phones without knowing the sender -- similar to the early days of email.