Page Lock on Browser Back Button after Page Expiry

In the attached quickstart, after page expiry and browser back navigation, a server error occurs such as:

"failed to acquire lock to page 0, attempted for 1 minutes out of allowed 1 minute"
This appears to be related to request logging, but I have seen other strange errors without request logging such as

org.apache.wicket.request.handler.ComponentNotFoundException: Could not find component 'form' on page 'class web.page.ExpiredPage

also with browser history back navigation.

I have seen none of these errors in Wicket 1.4. I guess the reason for not having seen this before it that http cache headers are different in 1.5.