I also have heated grips and about 7K miles on my bike. My story is a little different and might place some light on this issue. Instead of the grip breaking the throttle cable broke right at the edge of the piece that fits into the grip. This could only happen if that piece was stuck in the grip and didn’t move as the throttle was turned up and down. What is more interesting is that when I removed it that is exactly what I found. It was like the stuff they use so that the grip doesn’t stick to the molds when they are making them became hard and froze they cable pen in the grip. In 99 percent of cases this would break the grip but for some reason in this case it was strong enough to let the cable work back and forth until it broke. I have mine all back together now and my thought is to go about 1000 miles ( if it last that long)and take it apart and see what things look like. Just some food for thought.
I just bought my 2008 Touring on 7/26/2015. It has the heated grips. Yesterday the tab broke! Bike has 10800 miles and I put on 400 of those. Grumble. Only replacement grips I've even seen are the Kurakyn. No other options?