FCKEditor saving of teaser for nodes - spacing missed out

This is a bit of an odd one this one... The teaser as you know is generated from the 'Body' field. If you start your content with a header and then follow with a paragraph and then view the post teaser, the end of the header and start of the paragraph is joined together without a space.

So the following written in the rich text editor:

Header 3 style

A paragraph that follows.

...in the teaser gives the following:

Header 3 styleA paragraph that follows.

This is via creating a new page, using the rich text view and creating the post. If you afterwards go back and edit, flick to Source View, the structure is fine... you have

Header 3 style

followed by

A paragraph that follows

.
If you save it whilst in source view, the teaser is fixed and the space magically appears.

Additionally if you create a post from scratch, switch to plain view and enter the source code directly, you get your space... so it certainly seems to be something that the teaser field is picking up from FCKeditor's rich text view when initially saving the node.

Any ideas if it is fixable? (I checked the new release notes, as i'm due to update to the latest version, but didn't spot anything regarding this issue).