The same thing can occur when you have dropped your squeegie from a great height.
That's how it happened. I thought I couldn't remember trapping it in the car door! But I do remember dropping it from the top of my ladder!!
Aye, live and learn. I wish I posted something Wednesday evening about my 'bad batch of rubbers', then I wouldn't have had a rotten Thursday, Friday and Saturday (I worked today, 11am to 5 pm).
Once I worked out that it was my bent channel; I went to get Wor Lasses squeegie, but she'd taken it out to clean our own windows (which the 'Mad Get' does every week). I was really cross about that at the time.
So I ended up using a 26" squeegie (I'm guessing the size - a big one) on residential and spraying and scrimming those windows where the big squeegie didn't fit.
It's strange how something so simple can be so frustrating!!!