Warning about passing variables

I get the following error on pages after installing Simple Meta:

Strict warning: Only variables should be passed by reference in simplemeta_page_alter() (line 91 of C:\xampp\htdocs\deptosmendoza\sites\all\modules\simplemeta\simplemeta.module).

I don't know if I missed something for configuring the module correctly. All I did was set permissions but I didn't find any configuration option in Admin->Configuration nor anything about that in the readme.txt either. It does say there should be some kind of option or tab in Admin->Content but there's nothing there, just my usual tabs for content, comments and webforms and the options for each page to edit or delete.

It still seems to work okay though. I use the little floating-type Meta tab at the left edge of pages and add keywords and description and they show up in the source code for the pages as metas...it's exactly what I wanted, simple and not cumbersome. But I worry about the error and hope it's nothing serious.