Hi Fredrik,
Thanks for the follow up! I got the error msg from my SEOmoz dashboard. I just got it a couple days ago and the first crawl has been completed. I can also see in Google Webmaster a similar error msg. The old pages are on an older SSL secured site, but the domain is still the same.
For example, my old site was https://www.kellanapparel.com and now I don't use the SSL certificate and the website is hosted on a new platform (shopify) but with the same domain minus 's' (so now its http://www.kellanapparel.com). Maybe it's the case that the old SSL certificate is still valid and because the old content is associated on there it's still triggering? Would this make a difference?
Cheers,
Peter