Same kind of problem, here.
This has happened to me twice in the last couple of weeks with my K9/ABS Wee.
The first time, the bike had been sitting all day in the driveway on a relatively hot day (upper 80's, low 90's) and around 10pm that evening, after it had cooled to low 80's, upper 70's I was going to go for an evening ride. Bike started fine, idling at 1300 rpms. As I coasted down to the bottom of the driveway, in first gear the bike suddenly stalled. Now, in the street, it started right back up, idling fine. But as soon as I blip'd the throttle the engine would die. Start back up, give throttle slowly, it would die every time I got to about 2500 rpms. Took about a dozen starts and stalling before it suddenly was fine and I continued on my way with no problems during a ride of about 20 minutes. About a week later...
The second time was almost the same. The Wee sat in the driveway on a bit hotter of a day, upper 90's... that evening I decided to go for a ride around 10:30pm. I had filled the tank with fresh gas the day prior. I even opened the fuel cap to let off any "pressure" before starting the bike. Bike started fine, idled fine... stalled probably 20 times, anytime I would get to 2500 rpms. Nothing out of the ordinary on the gauges, no cryptic LED messages or anything. I thought I could hear the fuel pump more loudly than normal... running constantly, but I dunno if that was just my enhanced hearing and sensitivity from being a bit pissed at why it kept stalling. Finally, it just ran fine... by this time I was up to three bars on the temp gauge.
I didn't siphon out any gas or add any products to the fuel... haven't had a problem running the same gas for the last 4 or 5 days. I cannot get it to happen, on purpose.