1script - 4:01 pm on Sep 21, 2012 (gmt 0)
By the way: these errors don't only come to the non-www versions of domains. I've received a few for the proper www version. This probably means that that www domain is doing so poorly on Google that 1 visit is really-really 50% of the entire daily crawl budget. At least in my case it looks that way. So, I can actually believe that 1 visit could be 50% of the daily crawl budget for non-www domain if Google knows that this is NOT the canonical version.
Why do you need to crawl it then is beyond me. Perhaps for some technical reason that has nothing to do with ranking or indexing, perhaps some registrar-related business.
This made me think that the DNS error I've received on the proper www version probably means that for this domain Google has mixed up which is canonical and they probably think www is actually not the canonical version. Gotta go take a look!