Glad to hear your gear worked... you walked away, and the bike only took cosmetic damage.
Just for grins... you might go back to the intersection and see if there's any sign of oil, sand, gravel, or a painted stripe you might have lost traction on, or something else that might have started it... seems odd that on a normal paved road only going 30 MPH that you would have lost the back end. Any idea what the tire pressure was?
What Groo said was exactly what I was thinking. I almost never touch pegs in the vicinity of an intersection. They are full of sand and the muck that is leaking out of people's cars.
Also...I recently replaced the tires on my FJR. At about 150 miles, I was feeling pretty confident on them and gassed it coming out of a large parking lot. The rear slid out a little, and I didn't think I had given it enough that it should have. The next day, I took the bike to our local canyon and rode the **** out of it. Scrubbed the tires in real good, all they way out to the edges. I haven't had a repeat of that rear slide. As Dcarver said, I think the days of release agents is over, but new rubber doesn't seem to stick as well as rubber that is a little worn in. Maybe a combination of things just hosed you. Sorry for your get-off, but glad your ok...