Check the laws in your state. I doubt it says anything like “stay in the middle lane if you’re going to be in the highway for a while” or “middle is for general travel”, which means you’re probably the driver camping in the middle lane when you should be moving over.

I’ve been in the same situation, drives me nuts.

This is why it’s best to avoid asking questions and rather send messages that inform, when possible. Say things like “I’m going to do this unless I hear otherwise” instead of making it a question. I try to put the burden on them to change an action or simply give them the option to not reply at all.

Of course, sometimes it just isn’t possible.