No. You would have to ingest magnesium and have failing kidneys to develop hypermagnesia, which could lead to hypocalcemia. But stones are a result of hypercalcemia, so no worries there. Kidney stones should be less likely in the presence of additional magnesium, not more likely. The amount you get from an epsom salt bath is not all that much anyway.

Hypermagnesia is not good for your kidneys long term health, but is usually due to kidneys that are already failing...

Moreover, the magnesium sulfate in the epsom salts is not absorbed by the muscles. The ES just relaxes them, and the body quickly eliminates it.