Not with this bike, but others. Today's white paints usually use titanium dioxide pigment whigh is very stable, but clearcoats are a different story. They start out clear but oxidation and UV light can turn them yellow to brown. On my older Bianchi the celeste sky blue or bluish turquoise shifted to a greenish truquoise everywhere but under the brake cable housing.

If the color shifting is mottled or only in local areas it might be from chemical reactions with stains, like from your sweat. At this point there's not much you can do, except to accept it as a sign of character, like the yellowing of the varnish in fine old paintings, or along the edges of vintage documents. BTW- this happens on all colors, but is most noticable with light colored or white bikes.