^^ what they said. Your poly bushings are on the softer side, so you won't really have the "plastic on metal effect" you get with the hard poly compounds. The grease can be helpful to reduce squeaks though. We do suggest greasing the face of them. It is generally a best practice to grease them every other oil change.
I will add that we have recently began pre-lubing the poly housing. Yours was manufactured prior to this change. If you want to, you can simply push the bolt sleeve out, apply a small amount of grease, and re-insert the bolt sleeve. It certainly wouldn't hurt to do this, but again, isn't critical with the softer poly compound.
Soon we will offer other custom poly compounds, giving customers even more options. A couple of these will be much stiffer poly, and the lube will become much more important.