[Exim] STARTTLS command used when not advertised

I'm getting this from time to time with exim 3.31 as a client and 4.14
on the server.

2003-05-07 10:07:30 SMTP protocol error in "STARTTLS" H=gargamel.merlins.org (gargamel.svh.merlins.org) [12.234.173.253]:34843 STARTTLS command used when not advertised
2003-05-07 10:07:31 SMTP protocol error in "STARTTLS" H=gargamel.merlins.org (gargamel.svh.merlins.org) [12.234.173.253]:34843 STARTTLS command used when not advertised
2003-05-07 10:07:32 SMTP protocol error in "STARTTLS" H=gargamel.merlins.org (gargamel.svh.merlins.org) [12.234.173.253]:34843 STARTTLS command used when not advertised
2003-05-07 10:07:33 SMTP protocol error in "STARTTLS" H=gargamel.merlins.org (gargamel.svh.merlins.org) [12.234.173.253]:34843 STARTTLS command used when not advertised
2003-05-07 10:07:34 SMTP protocol error in "STARTTLS" H=gargamel.merlins.org (gargamel.svh.merlins.org) [12.234.173.253]:34843 STARTTLS command used when not advertised
2003-05-07 10:07:35 SMTP protocol error in "STARTTLS" H=gargamel.merlins.org (gargamel.svh.merlins.org) [12.234.173.253]:34843 STARTTLS command used when not advertised
2003-05-07 10:07:36 SMTP protocol error in "STARTTLS" H=gargamel.merlins.org (gargamel.svh.merlins.org) [12.234.173.253]:34843 STARTTLS command used when not advertised
(...)

The client (3.31) shows:
2003-05-07 10:07:35 19DQHR-0005Lb-00 => marc_adm_at_merlins.org <root_at_gargamel.svh.merlins.org> R=lookuphost T=remote_smtp H=mail1.merlins.org [216.200.201.205]* C="250 OK id=19DSOE-0005Sy-GE"
2003-05-07 10:07:35 19DQHR-0005Lb-00 Completed
2003-05-07 10:07:35 19DQ3N-0005Bg-00 => root_at_merlins.org R=lookuphost T=remote_smtp H=mail1.merlins.org [216.200.201.205]* C="250 OK id=19DSOF-0005Sy-4x"
2003-05-07 10:07:35 19DQ3N-0005Bg-00 Completed
2003-05-07 10:07:36 19DPbd-0004ws-00 => root_at_merlins.org R=lookuphost T=remote_smtp H=mail1.merlins.org [216.200.201.205]* C="250 OK id=19DSOF-0005Sy-Nt"
2003-05-07 10:07:36 19DPbd-0004ws-00 Completed
2003-05-07 10:07:36 19DPai-0004vU-00 => root_at_merlins.org R=lookuphost T=remote_smtp H=mail1.merlins.org [216.200.201.205]* C="250 OK id=19DSOG-0005Sy-FQ"
2003-05-07 10:07:36 19DPai-0004vU-00 Completed

I can't reproduce that at will.
When I try to send mail hand, it seems to go through
Any ideas?

gargamel:~# Mail -v marc_at_merlins.org
Subject: test

test