Weird key change
Okay, I'll be the first to admit that I may be a little over my head working with a full orchestral score. Initially, everything is as it should be. Key is concert G major. Flutes, oboes, violins, etc. have one sharp. Clarinet and Trumpet in three sharps. All expected.
At the eighth measure, suddenly, there appeared a double bar, and a kind of key change. All instruments are in their original keys except the oboes. They are now in the key of C; the sharp has become a natural.
Is it something I inadvertently did? If so, what did I do and how do I undo it? Or is it just some funky glitch I can ignore?