Why would Rochester try to trick Jane by being disguised as a gypsy?

I think that Rochester tried to trick Jane by being disguised as a gypsy while she was getting her fortune read in the library, because Rochester is trying to get certain information out of Jane. While Rochester was a gypsy, he knew a lot about Jane and he also told Jane that she is very close to happiness. This gives Jane a sense of hope after overcoming her skepticism, before she realizes that it is Rochester the whole time. I think that this could also be foreshadowing upcoming events in the novel.