Must be the heat

A day or so ago a motorcycle cut me off. i was driving, in the right
lane, with the pace, of the traffic. I had to hit the brake. I couldn't
understand it.
Today, we were in the right lane, in sparse traffic, moving about 5 over.
A car came from somewhere behind. I don't know if they were already in
the left lane or not since I wasn't driving and watching. He or she
pulled into the right lane about 6 inches ahead, of us. Wife had to hit
the brakes. The car then sped away. There was no traffic for a quarter mile.
A little later wife was in left lane about to overtake a semi. A p/u
came roaring, from behind us and around our right side and between us
and the semi. Wife had to stand on the brakes again.
It must be the heat.