That may be, but the "station" likely was owned by a corporation that may still be around.

The word "trademark" is not properly used as a verb.  It seems reasonable to infer that the logo was used to identify the station, which means that the owner of the station almost certainly had trademark rights in the logo.  Even if the logo wasn't registered as a trademark, the owner of the station still had trademark rights (registration is not required for trademark rights to exist).

Yes, you can.  Does that mean it's a good assumption?  No, but everything you posted points to it being a relatively safe assumption.

Do you really remember what you did and didn't sign 40+ years ago?

It's important to note that trademark rights result from use of a mark in commerce to identify the source of particular goods or services.  It seems likely that the original station long ago abandoned the mark.  As for the guy who contacted you in 2010, while his trademark registration might have expired (trademarks themselves don't "expire"), he's obviously no longer using the logo in commerce.