I think I tend to agree with traveler18, if I remember right even for high 30s I had gotten them from the check-in agents but the experience at the CX lounges is quite a different story.

there's once where my flight was delayed for an hour and the gate was changed from sth like ~3 to ~36 (and the boarding announcement was made quite all of a sudden since the plane suddenly became ready to board after the delay). I thought as a courtesy the lounge agent would give me one esp given the situation - but I (together with 2 more DM colleagues on the same flight) was bluntly turned away by quite a rude agent (with the name Celia IIRC) saying that it's for gate 40 or above only, no exception, even though for gate 33+ you're recommended to take the APM...that's also how I came to know about this rule of gate 40+. I can understand if there's a rule they need to follow, but her attitude was just completely unacceptable.

there's also one instance when I asked for it at the Wing F lounge for my KA flight (I checked in at ITCI so no gate at that time yet and hence could only ask at the lounge when I knew the gate), and one male agent claimed that it's for CX flights only - I said I have been getting it for months for my KA flights. I argued with him for like 1-2 minutes before he then reluctantly called someone else and confirmed that I was correct, but then he murmured that it's a new change in rule etc (although it's been "new" for maybe a year already at that time)...

my overall experience at the lounge getting the buggy coupon is just quite a bit worse vs. at check in...