As PETALSSAMPCLIENT-1, the problem is due to the usage of the API ComponentContext.getEndpoint(ServiceName, EndpointName) where the returned value is not checked. The returne value null should throw an error instead of to be set in the MessageExchange that will force the Petals router to find an endpoint satisfaying only interface name and service name.
Already fixed on the version 4.1 of the SOAP component because a message exchange creation refactoring was done