screen command makes space under the caption

Hi all.

I am trying to use screen 4.0.3-7 on cygwin-1.7.11 but it
makes a blank line under the caption line when I split the display.

In my .screenrc, caption is defined as the following:

caption always "Caption"

On my RHEL6.3 server, the caption lines are displayed
like the following figures.(the version of screen is 4.0.3)

(1) Right after executing screen
-------------------
|                 |
|                 |
|                 |
|                 |
|                 |
|                 |
|Caption          |
-------------------

(2) After splitting the display by C-a : split
-------------------
|                 |
|                 |
|Caption          |
|-----------------|
|                 |