[logback-user] Quotes doubled in logs?

Hi! I the logs of our application I noticed that quotes get doubled. For example: - app received xml contents: <?xml version=''1'' ?> ... Those are two single quotes before the 1 and then two single quotes after it. That is not valid XML so the app would refuse it, but is does not. So the doubled quotes must appears somewhere in the logging. We use slf4j 1.6.1 and logback 0.9.28. Could this be something in logback? Did anyone else experience something similar? Regards, David