A friend of mine gave me a thank you card recently and was in such a hurry to put it in the envelope that she tore it. Noticeably. She gave it to me anyway. I will keep it always because she knew me well enough to know that I wouldn't care if it wasn't 'perfect'. She knew that I would treasure the thought behind it. She is a great friend.
I think your friend will love the mug rug, warts and all.