I'm pretty sure Shimano puts threadlock on these bolts at the factory. I've found a red threadlock like film on new shimano derailleur pulley bolts when doing the first maintenance. Regardless, I have used threadlock for years and never had a problem getting the bolts out. I started the practice of using threadlock after a fellow rider lost her derailleur pulley about 40 miles into an 85 mile loop and after searching for 30 min for the bolt, we flagged a car down to give her a ride. You're probably safe without it and I got by for years without it but it won't hurt anything to use it.