NOTICE: LockRelease: locktable lookup failed, no lock

Today I run stress test on my Web server. Test is rather complex
modperl script which does some manipulations with postgres (6.5)
database. In error_log I found:

NOTICE: LockRelease: locktable lookup failed, no lock
NOTICE: LockRelease: locktable lookup failed, no lock

I'd like to identify which process wrote there message.
Are these messages come from postgres backend ?

Regards,
Oleg

_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83