Wait to hear back from Andrew - he'll have a viewpoint with the advantage of deep experience.
But you DID torque the nuts, using LocTite, right? LocTite Blue 242*?
The reason I ask is that with the rack stays on the inside, a nut loosening and falling off leaves the thing setup such that a sharp turn could pull the rack loose from that side. If the rack is on the outside, even if the nut fell off your rack would be fine. Alternately, you could install the screw from the inside - this would avoid having to bend the stays and would give you a more reliable setup. To lose a rack fastener, you'd have to have the nut fall off AND the screw completely back out of the hole.
Then again, I'm an engineer and I may be overthinking this.
*"Blue LocTite" is generally meant to specify a threadlocker that is removable using standard hand tools. Whereas "Red LocTite" is meant to be permanent.