If I would be the doc, I might now send UA's headquarters some swiss chocolates, saying in the accompanying something like:

"thank you for having given me the opportunity to act as a samaritarian on UA flight NNN on dd-mm-yy from XYZ to ZYX. I appreciate that I was invited by (first, last name, UA-function) to performe some medical service to one of your passengers (first, last-name) and at the same time to avoid any rerouting of that flight. I hope that you will accept these genuine swiss chocolates as my gift of appreciation - signed doc-Rudi, address,"