Talking much about oneself can also be a means to conceal oneself [yes/no]?

Speculative and without evidence to either say yes or no. 

Yes, I can see that happening. If a person is talking all about themselves as if they are telling their life story, they may give out enough information that a listener might think they have heard everything there is to know about that person, and not think that that person has anything more to learn about or may have kept hidden.

Well mike, it can actually mean both depending on what you disclose. because if you reveal the whole honest truth you are opening up and not  concealing anything .on the other hand if you withhold things about you're real innermost self you are concealing yourself because nobody will know the real you, only yourself, l hope this makes sense