Hello - I've only recently begun to use gold toner, so I'm not an expert. Also I don't know what happens as the toner ages.
But it is a characteristic of gold toner to tend to deepen shadows (bluey-black) and lighten highlights (so it extends the tonal range). I haven't had a problem with highlights myself but I was aware not to have them too light in the first place - both because of the extended range with gold toner, and also of course there has to be some tone in the print to go blue, so if your highlights are so light they do not actually have tone, they won't turn blue, they will just go lighter. I haven't used it with lith so don't know if there are particular issues with that.