[Exim] redirection process vanished unexpectedly

Hi.

Yestarday I've upgreaded one of my exims (from 4.10 to 4.12). Today I
noticed strange lines in its logfile:

Jan 20 23:18:26 spruce exim[98503]: redirection process 98515 vanished
unexpectedly
Jan 20 23:18:26 spruce exim[98503]: redirection process 98516 vanished
unexpectedly
Jan 20 23:18:27 spruce exim[98517]: redirection process 98519 vanished
unexpectedly

It seems the message shows up in random places. At first I though it's
connected with exim filters, but not every incoming mail for the
particular address (with filter attached) causes this.

What can cause such line to appear?

Exim 4.12 with mysql on FreeBSD 4.6.2

regards
Przem