Why error messages for nonexistent jsp pages in logs?

I am seeing error messages for nonexistent jsp pages in my logs.There are no equivalent .cfm pages. We're on version 7.02. Examples:

In Coldfusion-out.log:

07/07 20:22:39 error Requested resource '/is/api.jsp' (%2fis%2fapi.jsp) not found

This is a valid directory but there is no such file

In Coldfusion-err.log:

07/07 19:42:28 error Requested resource '/is/admin.jsp' (%2fis%2fadmin.jsp) not found

This is a valid directory but there is no such file

In Coldfusion-event.log:

07/07 20:22:50 error Requested resource '/is/service.jsp' (%2fis%2fservice.jsp) not found

This is a valid directory but there is no such file

Thanks in advance for any help!

Richard