CAS 3.0 Java Client Servlet Exception when the given ticket is expired.

[Matteo Matteo]

We loaded one page, there's a ticket in a browser request string (method GET) like
http://workstation95.local.workgroup.de/cas4/?ticket=ST-12-XhBDMGOOdfKy72Y1GdLvbnj6WE7UucV9ams-20

if you try to reload this page - you'll get a servlet exception because this ticket is not valid any more. This behaviour looks a bit strange, because as for me it should in this case automatically redirect to CAS server, or not?
The same problem was with a CAS client 2.1

Below are error messages:

=======================================
HTTP Status 500 (Apache Tomcat/5.5.16)

javax.servlet.ServletException: 
		ticket 'ST-12-XhBDMGOOdfKy72Y1GdLvbnj6WE7UucV9ams-20' not recognized
	
	org.jasig.cas.client.web.filter.TicketValidationFilter.doFilterInternal(TicketValidationFilter.java:109)
	org.jasig.cas.client.web.filter.AbstractCasFilter.doFilter(AbstractCasFilter.java:100)
	org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:138)
	org.jasig.cas.client.web.filter.AuthenticationFilter.doFilterInternal(AuthenticationFilter.java:97)
	org.jasig.cas.client.web.filter.AbstractCasFilter.doFilter(AbstractCasFilter.java:100)
	org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:138)


root cause 

org.jasig.cas.client.validation.ValidationException: 
		ticket 'ST-12-XhBDMGOOdfKy72Y1GdLvbnj6WE7UucV9ams-20' not recognized
	
	org.jasig.cas.client.validation.Cas20ServiceTicketValidator.parseResponse(Cas20ServiceTicketValidator.java:80)
	org.jasig.cas.client.validation.AbstractUrlBasedTicketValidator.validate(AbstractUrlBasedTicketValidator.java:48)
	org.jasig.cas.client.web.filter.TicketValidationFilter.doFilterInternal(TicketValidationFilter.java:91)
	org.jasig.cas.client.web.filter.AbstractCasFilter.doFilter(AbstractCasFilter.java:100)
	org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:138)
	org.jasig.cas.client.web.filter.AuthenticationFilter.doFilterInternal(AuthenticationFilter.java:97)
	org.jasig.cas.client.web.filter.AbstractCasFilter.doFilter(AbstractCasFilter.java:100)
	org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:138)