I wonder what is happening that can create a pitot blockage in five minutes.
Nothing has happened. On Hamilton Is during the 80s, we reckoned that there was a mud wasp that would sit near the terminal building waiting for us to land and shut down. Within a few munites, if we did no put the pitot covers on, it would have started building a nest in the head.
It is not only pitot heads that are a target for mud daubers. I have had Citation pressurise on the ground after engine start as a wasp had built a nest in an overboard vent. Our solution was to put a piece of paper in the tube that would be blown out by the venting airflow.