When did you do the changes and when did Google say that had problems caused by DNS?
I guess you shouldn’t have this problem if you simply updated personal details in your WhoIs registry but if you changed the DNS servers, it can take up to 48 h to propagate worldwide.
True. However, some time back, Google started reporting it couldn’t access the robots.txt file on one of my sites. I could, as could anybody else I asked. Bing had no issues, only Google. I’d made no changes to the file or the hosting since the site first went up, and Google had previously had no problems. This went on for several weeks, and nothing I tried had any effect. (e.g. deleting the file and uploading it again.) Then the problem vanished as mysteriously as it appeared. I never did get to the bottom of it.
Then I guess we should ask Google direclty because they’re the only ones that can check what’s behind.
It is strange enough that Google can’t access a robots.txt file but I assume that a DNS error is, mainly, caused by the registry company or wrong data input. That doesn’t mean that it may not be Google’s fault. Maybe is a bad cofiguration in one of their gateways or firewalls. That could also cause errors accesing some websites.
If it’s a temporary problem with the name server it’s mostly out of my control and not much I can do but be patient and wait.
I will keep an eye on it and if it persists I guess I could contact my host and pester them about it. But for now I’m not going to do anything about it.