You are so right to feel that way. I have a gal who does charity quilting on her long arm for me and also does it for free. I usually make her something and add a gift card to sweeten the pot. My gal is always busy with her quilt business and I feel she should be rewarded for her time and talent. I might add that she receives a tax letter credit for the work as well.
I never put her on the spot under a short deadline. I know she appreciates that.
All that being said, if you have the time and wish to barter another type of work she is not able to do, like yard work or sewing, maybe she would consider a barter of time for time?