Every once in a while I have encountered similar drink experiences. One time the front of the cabin (I was in the back) was placing orders for drinks and the FA was swiping cards and taking coupons. When the Aft FA came to me I ordered and received my drink without charge. When I ordered my second one I asked about my tab and he said "You are ok". Enjoyed four drinks all comped while the front was paying. Another experience from BWI to SAN all the drinks were comped (the flight left one hour late)

My worst experience was last year in November on a flight from SJC to LAS and the senior FA was curt on her welcome message on our full flight and stated for us to have our coupon ready or CC ready or we would be passed by. Also she said one drink only because of time. After I finished my one drink the service was only mid flight and had not even started to descend yet. I called for another drink and was refused and told booze cart was sealed. I complained about it and the Senior attendent came by and firmly said only one drink for all flights unless it was a two hour flight due to some legal thing.
I told her that this was BS but she was firm about it and left.
Hope I never get her again on a future flight