Yes, happens a lot...
I'm noticing it in .153 but I'm not sure if it's that new.
I have a habit (2+ years) of pausing Slacker when I leave the car. When I return to the car, I resume playing as part of my sequence of getting underway. I'm pretty rigorous about it. I do a lot of "save this song for the next drive" -- which is very handy with the buffering when you park underground (out of 3G range).
I've noticed (mostly not underground) that lately when I return to the car Slacker has already resumed (and sometimes is playing a different song than I left). Anybody else run into this?