Salad Leaf Identification

I pulled a strange leaf out of my salad today. The leaf has lost its stiff, crunchy texture became soft, wilted. This altered appearance makes the leaf hard to identify. In this brand of salad, iceberg lettuce is traditionally used. Iceberg lettuce has the appearance of an even light green color with some mild discoloration around the edges of the leaf. The stem of an iceberg lettuce leaf is also quite large and stiff. The leaf specimen I extracted from the salad has a thin, light green stem. The whole leaf is also discolored so that it is a mixture of dark purple and green. The dressing seems to be obstructing important characteristics about the leaf that could have led to an easier identification. From the stem to the opposite end of leaf it appears to be approximately 3 inches long. Again this seems like a strange length for a piece of iceberg lettuce. Perhaps this leaf was trimmed or it has no relation to iceberg lettuce and is instead a smaller leaf.