I have "quite a few kilometers more" than 30K with Kuryakyn grips. Never had a problem previously, but the last two issues I had with the Kuris on my R3 kind of killed the issue for me.
I went ahead and re-installed the stock Triumph grips while I look for new ones.
Do a Google search for "Kuryakyn ISO grips fail." There's a long thread on the issue on the triumphrat.net site. And other places. It happens. Not just with Triumphs, but with HDs and other bikes. Just a weak tab on some of their ISO grips.