[goodpoint]

> just running the software on my machine can potentially create a legal obligation

Not true: only if you made local modifications.

> I forgot to block a port

Also not true. You have plenty of time to close that port.

"""your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice."""

If you expose services on the Internet by mistake you are going to have 1000x bigger problems than the risk of being sued successfully for a honest mistake.