Can anyone think of any examples of this happening in sonata form movements? Seems like an obvious way to bring some variation to the recapitulation while keeping it sounding like a recapitulation. I know this happens sometimes with the second theme group like in Mozart's String Quintet in G minor but I don't remember ever hearing this with the first theme group.
edit: I mean first theme group in minor key in the exposition, but major in recapitulation, or the other way around (not changing in the middle of the recapitulation), or perhaps changing between other modes.