Featured posts arrows not visible without custom heading

Hello,
after the upgrade to 3.1.0 I played little bit with settings in Customizer and I found one issue with Featured posts visible on my blog. I setup more featured posts, so the arrows and the small buttons appeared above those posts. However, the arrows are not very visible – they are “hidden” behind the menu (I use header menu). The arrows are correctly visible only when I setup “Display a custom heading for your blog”.
I am not sure if it is only my issue, or it is something general. Can you please help?
Thanks.
skubko