how to get rid of white lines between lines and fills when saved into pdf

[Banila4]

I got this when I save from Illustrator into an pdf. How can I get rid of thes white lines between lines and fills?

Thanks for your help.

Ton

[Monika Gause]

Is this Live paint?

It gets automatically expanded when exporting to PDF. 

Those look like 2 different blacks. Is that correct?

What's happening here: that is an antialiasing issue. It will most probably not print (but can still happen on some desktop printers or in Large Format - depends on the RIP).

To prevent that you would have to stack shapes that at least slightly overlap.