debug nonstandard use of \\ in a string literal

Hello,

From time to time I face with these well-known warnings in the
PostgreSQL log, i.e.

Feb 28 04:21:10 db7 postgres[31142]: [2-1] WARNING:  nonstandard use
of escape in a string literal at character 62
Feb 28 04:21:10 db7 postgres[31142]: [2-2] HINT:  Use the escape
string syntax for escapes, e.g., E'\r\n'.

This is fine, everybody knows about that and our PL/PgSQL developers
try to make use of escape syntax. But sometimes errors occur anyway
(by developers mistakes or something). So the question is: how to
debug these annoying messages when pretty big application causes them?
Is it possible to have a look what exact queries produced them?

--
Regards,
 Ivan