Lawyers are free to contact witnesses, and frequently do, and in fact are supposed to so they know what the evidence in their case is. The communications aren't attorney-client privileged, so that information is discoverable, but it's perfectly legal.
Why aren't you asking your own lawyer?
I'm only licensed in CA. Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.