Yeah. I guess the best description as it felt as if it was swaying just a bit side to side, which is where I thought about that extra room in the bolt hole allowing some movement. My thought was if it was actually threaded into the frame, that movement would be much harder to achieve, the bolt would be fixed more in one place than tightened through a hole slightly larger than itself.

There are a few variables I'm trying to work through to pinpoint the issues exactly, it may well just be the rack design itself. Mostly just curious on people's opinions of thru-bolt v threaded for mounting, and if there is any harm or benefit to doing so on a bike that wasn't originally equipped with it before breaking out the drill and tap. The girlfriend's had a threaded eyelet, it made installing things much easier anyhow.