The cellist and teacher Madalena Sá e Costa was the grand-daughter of the founder of the Orpheon Portuense, and she recalled the many famous musicians whom she had the opportunity of meeting in her childhood - including Ravel who gave her a gentle kiss on her forehead on the occasion of his visit to Porto in 1928:
"Nomes cÚlebres, como o de Maurice Ravel, acabado de compor a sua sonata de violino e piano, uma linguagem musical recebida em apoteose. 'Eu tinha 13 anos, lembro-me que me deu um beijinho na testa, afável.'"
("A mulher dos mil concertos abre álbum da memória", Diário de Notícias [Lisboa], 23.ii.2008.)
In November 1928 Ravel undertook a concert tour of Spain and Portugal. He was looking forward to drinking "un porto à son pays d'origine". (Orenstein  letter 304). It had been proposed that the tour should begin in Portugal with a concert in Lisbon but it is not clear whether this actually took place. However after visiting a number of Spanish cities, Ravel did conclude his tour with a concert in the city of Porto on Saturday 24 November. He was accompanied by the singer Madeleine Grey and the violinist Claude Lévy.
The musical society Orpheon Portuense had established a tradition of bringing leading musicians of the day to present their own music, and its director Luiz Costa extended an invitation to Ravel. Many of the works in Ravel's programme in Porto were being heard in Portugal for the first time. The works included the Prélude and Menuet from Le Tombeau de Couperin, Habanera, the Pavane pour une infante défunte, and the Sonate pour violon et piano; Madeleine Grey sang Ronsard à son âme, three Mélodies hébraïques, and two arias from L'Heure espagnole and L'Enfant et les sortilèges. (Arte musical [Lisboa], III Série n.1, Março de 1958. p.11.)
(Thanks to Edward Gonçalves Pinto for providing this information.)