Neither the regimental colors nor the national colors of the 104th Pennsylvania Volunteers were captured by the Confederates at the battle of Seven Pines. Writing in his memoir, William W. H. Davis, the Colonel of the 104th, wrote notes the story of the rescue of the colors by Major Gries and Sergeants Myers and Purcell. He states explicitly in two places (pages 102 and 106) that the flags were returned to the regiment. See Davis, W.W.H. 1866. History of the 104th Pennsylvania Regiment, from August 22nd, 1861, to September 30th, 1864. Philadelphia: Jas. B. Rodgers (reprinted 2000 by Higginson Book Company).
Personally I'm tired of correcting this misconception. Colonel Griggs was wrong. The colors in question are in the collection of the Commonwealth of Pennsylvania and the Bucks County Historical Society. Check your facts before you publish anything -- one source is not enough!