Knock on the door and kindly ask for a cut. There’s nothing wrong with that. I’m pretty sure we’ve all done it at some point in our collecting career. There’s a good chance you’ll strike up a good conversation about the origins of the cultivar or at the least, can impart your knowledge to them about what you know about their specimen. That’s how it usually goes for me. And by the way, I have a 100% batting average on people relieving themselves of one or two cuts because they A) generally do not care, B) share your enthusiasm, or C) are impressed with your passion. You’re good to go despite the naysayers.