2003 R1150R Single Spark, Non-ABS, just over 39,000 miles.

During the past couple of weeks, my bike's been popping out of gear during hard acceleration.

It's only happened a handful of times over the past few weeks, usually while accelerating on a freeway on-ramp, in 4th or 5th gear, over 4,500 to around 5,000 rpm. The bike pops into a false neutral, I put it back into gear, and continue on my way as usual.

Today, as a first step, I changed the FD and tranny oil (it was due), using synthetic 75W-90.

Anyone have any experience or ideas of what I may be dealing with?