I think that is a flash error. (I don't have a Rebel any longer) You may have gotten some dirt or something in the mech that flips it up. When it tries to flip up help it with your finger nail. You can try to clean the area with a qtip and denatured alcohol.
EB
EOS 1D, EOS 1D MK IIn, EOS 1D MK III, EOS 1Ds MK III, EOS 1D MK IV and EOS 1DX and many lenses.
