Hey I have a feeling the prob is with your system's db libs. Was that a fresh 4.10 install or have you brought it to this level from earlier 4.x.x versions by "building world"? If older db perhaps need to upgrade libs.. I've had to fiddle with this on certain apps, squidGuard comes to mind.. needing specific BerkleyDB versions.. the postgrey docs make no mention of db version.. hm
Just a guess, but I think it's nothing to do with Perl .. IIRC the postfix build doesn't require specific db libs, can work with older ones, it won't complain.. so you'd never get a complaint..
if you do get a reply from the author I'd be interested in hearing any comment..