Only variables should be passed by reference

I have a node participation which contains 2 node references (course & person).

After I've created a new person-node with the add dialog, I receive a strict warning when i try to save the original (new participation) node. The message states:

"Strict warning: Only variables should be passed by reference in references_dialog_redirect_page() (line 433 of mysite\sites\all\modules\references_dialog\references_dialog.module)."

Both nodes (person via add-dialog and participation) are created but with this warning-message.

I've seen this behaviour on both the alpa1 as the dev version....