I have been having similar problems but at lunchtime.
I have been on a pump for 4 months now, and have gradually reduced basals - with basal testing.
But I have also noticed that post prandial lunch problems have been increasing, and recently have linked those 2 factors, as i think ??? that my previously higher basals were supporting my lunch carb ratio. So I have just updated lunch ratio - more insulin.
As you mention some high readings pre meal, I wonder whether either higher readings are raising your insulin resistance on those days, or whether it is a combination basal bolus effect.
PS, I am not sure I have sorted my settings out yet, more testing necessary.... great.