I have a car for sale in Autotrader and I received a text message from number 469-284-8326 also.
The text said Hi is your vehicle still for sale. My ad was only a week old in Autotrader.
There have been reports on this site that the web site they direct you to to get the report is bogus. Most likely they want you to enter your credit card information and then they will use it or sell it.