I see these messages in Tomcat's log on Confluence startup.
I don't see any troubles caused by this errors, but I think you should know about that:

PANIC : error configuring SimpleLog4JLogSystem : java.io.FileNotFoundException: velocity.log (Permission denied)
log4j:WARN No appenders could be found for logger (org.apache.velocity.runtime.log.SimpleLog4JLogSystem).
log4j:WARN Please initialize the log4j system properly.
Jun 18, 2004 3:34:36 PM com.opensymphony.webwork.views.velocity.VelocityManager loadConfiguration
INFO: Initializing velocity using 'velocity.properties'
PANIC : error configuring SimpleLog4JLogSystem : java.io.FileNotFoundException: velocity.log (Permission denied)
Jun 18, 2004 3:34:37 PM org.apache.catalina.core.StandardHostDeployer install