[exim] nwildlsearch failure

Is this expected behaviour from nwildlsearch?

Example 1: It finds a match for neil.youngman@??? but a look
up of bad.example.com returns NXDOMAIN. The condition fails, in spite of
having a match.

>>> neil.youngman@??? in "neil.youngman@???"? yes
(matched "neil.youngman@???")
>>> no IP address found for host bad.example.com (during SMTP
connection from mail-ed1-f53.google.com (test.wirefast.net) [209.85.208.53])
LOG: no IP address found for host bad.example.com (during SMTP
connection from mail-ed1-f53.google.com (test.wirefast.net) [209.85.208.53])
>>> host in "bad.example.com:^^mail-.*\.google\.com$"? no (failed to
find IP address for bad.example.com)
>>> accept: condition test failed in ACL "acl_allowed_rcpts"

Example 2: It finds a match for neil.youngman@??? and does
not try to look up bad.example.com. The condition succeeds.

>>> neil.youngman@??? in "neil.youngman@???"? yes
(matched "neil.youngman@???")
>>> host in "^^mail-.*\.google\.com$:bad.example.com"? yes (matched
"^^mail-.*\.google\.com$")
>>> accept: condition test succeeded in ACL "acl_allowed_rcpts"

Neil Youngman