Glad my suggestion worked for you, Calista! Green tea will enhance coppery red highlights. Celestial Seasons' Red Zinger tea will enhance red highlights. I had better results with green tea, until I oversteeped and ended up with the same problem you did. I haven't played with it since because I decided that I look best with my hair color the way it is. The one thing I really do like about tea rinses is they wash right out. Very temporary; no committment.
Glosses: I did a henna gloss way, way back when Valentina first introduced them to us at LHL. More than one, I think. It was very subtle, and I think I'm the only one who noticed. But if anybody tells you that they wash out over time, they don't. I couldn't see a line of demarcation on my brown hair as it grew out, but one day I noticed that all of my silvers (fortunately few at the time) had more of a gold tint to them as they grew out. Henna, even in small doses, is forever.