I'm doing some poking around, just because that's what I do. Browsing speed is excellent this morning. I noticed the issue last night moving into forums.

I get the insecure warning on some but not all NAT pages. On the threads that were created after the switch to https, most are now good. But if someone has a link to an image in their signature (for example, weather image in Mike Shimek's), I see the yellow warning.

Going into older threads, I can see the warning even when there aren't any obvious images on the page. It could be one of the navigation buttons was triggering it. But that's history now, so I'm going to ignore those.

edit:

now if the issue of being dumped back into the forum list after posting gets resolved, then life, the universe and everything will be resolved again.