30 miles is very close to fault of that magnitude.
Thirty miles does sound close. Still, if it’s not the New Madrid fault then New Madrid pressure relief or build-up would be affected differently.
If it was the New Madrid fault, it could be seen as relieving pressure in the region, possibly a good thing. If it’s a secondary fault, I believe it could only be seen as adding pressure to the New Madrid fault, not a good thing.
We have a number of known fault lines in California, and we’re learning of new ones all the time. Although some of them are within ten to twenty miles of the San Andreas fault, they still aren’t considered to be a part of it, and when they go off, they aren’t considered to be quakes involving the San Andreas, even though they may be affecting it.