I actually figured out, for the same thing I feel, that it was because of my clothing, specifically my Aerostich..
If I mounted the bike, and just took off, it would happen pretty rapidly, like within 20-40 minutes..
Now, when I get on the bike, before I sit down (with sidestand down), I stand up, and pull my Stich pants up, tight in the crotch, then sit.. it surprised me that it was soo simple. My Suit fits me very loosely, and it seams it kinda pulls my hips when it's "baggy" on take off.
but.. it's also apparent that age takes it's toll also...