Yes, and there is a solution. Ask your local friendy Cat Dealer to apply the After-Failure Service Letter to replace the bonded windows with "old-fashioned" zip-in windows. Also tell them to make sure they order 2 window kits per machine because each one only contains enough material for 1 door.
The Service Letter is document reference REBE8225 titled "PRODUCT SUPPORT PROGRAM FOR REPLACING THE DOOR GLASS ON CERTAIN 12M, 12M 2, 14M, 16M, 120M, 120M 2, 140M, 140M 2, 160M, AND 160M 2 MOTOR GRADERS". There is also a Service Magazine SEDP1420 dated 4/4/12 titled "Zip-In Window Door Kits Are Now Available on Certain M and M-Series 2 Motor Graders".
To install the kits they need Special Instruction REHS4389 titled "Installation of Zip-In Window Door Kits on Certain M-Series and M-Series 2 Motor Graders"
Quote that lot at them and their heads won't stop spinning for a week ............