The Rub is an attempt to warn you in that moment that your set boundaries are being violated. The rule for staying in your lane at the cost of safety to you and others is in jeapordy when one hears and feels this Rub on the road.
Currently I am in a Rub of Life. The Rub that God has placed in my life that I continually keep bumping into or rolling over is Understanding God's Healing Process. As I or friends or family members get sick and need prayer - I pray. Many times the cases are serious, like at this writing my Dad is in the hospital and been there for days and I have prayed earnestly quoting Scripture and the promises of God.
I am not meaning to treat God like a genie in order for instant gratification, I am looking at how people in The Bible were healed instantly at His touch when they approached Him by Christ's compassion. They were especially noticed by Jesus and their situation taken care of when people displayed faith in Christ's authority as Messiah and healer.
The Rub has come in the past when I have prayed for people's condition and not only did they not get well, they died. The Rub is coming now as I have a host of prayer warriors praying for my Dad and not only is there no answer, the specialist doctors can't agree on the plan of attack. Frustrating in both the natural and spiritual realms.
I base a large part of my view on praying and getting answers to prayer on Christ's very words in Mark 11:24 - "Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." However, when my faith as a Christian does not see the immidiate action that I expect, The Rub begins and a crash is emienent unless I can gain the proper perspective.
There is no other avenue I have but trust. I have to back away or navigate away from my boundry of Understanding God's Healing Process and surrender all my attempts to grasp His ways and plans. My Dad and I and many others are perfect examples of experiencing God as same in nature but different in His processes (sometimes immediate, many times lengthy). This is why trust is is relearned so many times, at least in my walk with The Lord, as I continue to keep hitting The Rub.