Ace's original (smaller) American flag pin appears to be true vintage, "Vietnam War" era, according to this seller:
The shape, number of stripes, and even the starless wedge of blue to the right of the field look to be the same, each has only eleven stripes, and the relative size is appropriate, given the proportions of the backing.
Still no sign of the larger "Survival" flag pin, though the shape is very similar to Union Jack flag pins I've seen, and "Friendship" (flags crossed) pins, though nothing of the right size for Ace.
Speaking with ktbergeron earlier, I pointed out that Ace wears different jackets in the same serials: she clearly had the Paratrooper patch on her left elbow during one scene in "Curse of Fenric" but you can clearly see her wearing the soccer ball patch in its place as she climbs down her rope ladder. And in "Battlefield," while entering the catacombs beneath the lake, the Columbia mission patch is clearly visible, and her American flag pin is so small it's barely noticeable; but when she emerges from the lake with Excalibur, the Columbia patch has been replaced with the Atlantis patch, and the flag pin has gotten much larger -- to the proportion of the one from "Survival," it seems.
Looking forward to a comprehensive analysis of each different configuration!