VNC delayed startup on RasPi3A+

Running the latest image, update/graded on my brand new 3A+, I find that the VNC server takes about ten minutes to start up, unless I plug an unpowered USB1 hub and a USB1 mouse in - then it’s ‘immediate’

I can use the same microSD card on a ZeroW or a 3B+ without the problem.

Is it a duff Pi3A+, or is there a known problem?