If you weren't paying for XM before and suddenly started getting the alerts that was because XM just had offered 2 weeks of free service that ended on the 29th.
I have XM but only for music, but I started getting traffic alerts over this period. That comes from their Traffic and Weather Serivce that is extra cost. It actually helped me out when we where on the way to the airport to pick up our kids and grandkids. We had two accidents and debris from an overpass snarling traffic, but at least I could see what, where and how long the delay was. It was nice but I still won't pay for it. I'm cheap.