As Peloton’s stock price began to tumble last autumn and just months after a costly recall of the connected fitness company’s expensive treadmills, its executives were confronted with a new crisis.

In September last year, staff at Peloton warehouses, which receive high-end bikes originally manufactured in Taiwan, noticed that paint was flaking off some of the exercise machines.

The cause was a build-up of rust on “non-visible parts” of the bike—the inner frame of the seat and handlebars—and did not affect the product’s integrity, Peloton recently told the Financial Times.