I'm curious, has anyone had any interactions with LE while carrying a polymer 80 pistol?  i'm curious how it went, considering that your average cop might not know that a homemade pistol is legal in WA.

I guess this would depend on what type of interaction. The 2 times I've been pulled over while carrying, they didn't even look at the firearm, just wanted to know where it was. When talking with others about the same experience, most officers don't look to closely at the firearm aside from wanting to know where it is or moving it to a location out of reach of the driver or passenger.

How'd they know about the gun?

Your CPL flags when they run your plates or license and then they ask you about it.

Both times I was going to and from work. Unfortunately my work does not allow firearms inside the building, so the firearm stays locked in the glove box while I'm working. Both times I took the time to inform them where the firearm was before reaching towards the glove box to retrieve my paperwork. The first time this happened, the Trooper opened the glove box, reached in, grabbed my paperwork, and that was it. The second time, the trooper let me grab the paperwork and then close the glove box. Nowadays, in my new vehicle, I have a separate place that I can keep my paperwork.

Thanks for the replies.  

Get one of those visor organizers.(for the registration, not the gun) I've been using them for about 20 years.
BTW, the glove box is about the worst place for a gun. First place a crook would look. I've carried guns in vehicles when I couldn't carry at work, always found a place to hide it under a seat, behind a seat, etc. One car had those pouches on the back of the seat, then I happened to have seat covers over the seats. I had to reach up under the cover to find the opening to the pouch. Only way you'd ever know a gun was there was if you pat down the seat and felt the buldge.

As stated, my new vehicle has a separate spot that I can keep paperwork.

While a glove box is one of the first places someone would try, it is in still in compliance with the law and something that can't be easily removed from the vehicle. It also isn't just shoving the firearm somewhere in hopes that someone won't see it without it being secured somehow.....