migrating 2.3.17 to 2.5.8 s:url works differently

[McGregor, Chuckles]

In our current 2.3.17 app we have working in  s:urls in the form of <s:url 
var="remoteurl" action="jsonGenericGrid?gridType=ANL" />
But generate the message is no Action mapped for namespace [/anl] and action 
name [sonGenericGrid] associated  where the  jsp is anl/grid.jsp with version 
2.5.8
I worked around the issue by changing the url to <s:url var="remoteurl" 
action="jsonGenericGrid?gridType=ANL" namespace="/" />
Is this a bug or the way things work in 2.5.8?