I've had the same problem on my windows phone. I think it's an issue with StartSSL certs that are not trusted as much as others.
That seems likely. If you can't add StartSSL to your chain of trust, the same page can be accessed over HTTP instead of HTTPS.
Noted - thanks.
Yes, still happening for me.
As suggested above, this is probably because your browser doesn't trust StartSSL. If you don't want to add them to your trusted certs, the same page is available over HTTP as well as HTTPS.