Yep common fault on these. The pencil trick followed by adjusting the fan overrun and fan startup rate stops it from recurring.
It's condensation forming on them normally. Adjusting the fan speed and overrun dries it out after use.
Process is as follows to prevent those nuisance recalls for ya.
Hold the spanner button until display changes (10 seconds) and shows 1a.
Release button. Use the eco button to navigate to "5b".
Press the chimney sweep button once. It will. Now glow orange and display current setting for that parameter (fan overrun).
Change this parameter to "18" (180 second fan overrun) using the "eco" button.
Press and hold chimney sweep button until display shows "[ ]"
Now hold both the "eco" button and the briefcase symbol button simultaneously and hold until displays shows "8A".
Press the "eco" button to navigate to parameter "9d"
Press the chimney sweep button once.
Change the parameter fan (start fan speed) using the eco button until it reads 55.
Press and hold chimney sweep button until display shows "[ ]"
Now press the spanner button once to exit service levels.
Hopefully that's clear and helpful.