Well the bolts are definitely stretching, not turning loose. I torque them, and marked their position. Then I'd go riding, and then torque them again to the same value, adding approx 1/8-1/4 turn after each ride, but not always the same bolts, or all of them. After 3 rides, I went to torque them again today and the one felt like it was going to break so i pulled it out..a solid 3/32" longer than the rest...I pulled out all 4 and they were all different lengths...could just tell by eyeball.

I happened to look at my old Deore XT crank I replaced earlier this year. It had steel bolts so I put those into my road bike this morning. Torqued to max-141inlb, and marked position. We'll see how this afternoon's ride goes.

Matt