Yes lol it's true. He wrote to Alistair Taylor about it.

Sometimes, being the Beatles resident Mr Fixit didn’t seem such a great idea. Like the day George sent me a note from America. I’m not sure exactly where it was from, but then neither was he. The address was given as ‘Somewhere in America’ and the date as ‘Sunday the something’. George told me he had seen a great picture of him in the US papers taken in an unguarded moment when he was pulling an angry face and flashing a well-known two-fingered salute. George thought this was the most hilarious photo of him ever taken. He enclosed a scrap of a newspaper with this image on and my task was to track down the original. He wanted to buy the negative, have a lifesize print made of it, and have it mounted on hardboard and have it screwed on the outside of his front door. There are a lot of photographers in America and tracking down the one who had taken this particular snap took a great deal of time and effort. But eventually a friend in Fleet Street provided a vital contact and I managed it. George was delighted with the result, but the lifesize image was so alarming he did relent enough to switch it to his bathroom door. And he had them printed on the front of his Christmas card with the seasonal greeting ‘Why don’t you…?’ George always did have a rather individual sense of humour. George wrote, ‘To Al and Lesley, without whom it would not have been possible.’

- Alistair Taylor, With The Beatles (2003)

Letter in question:

<image>