Your company will not fir you becuase you knew about your boss's leaving. If the bigger boss asks you about it, tell the truth. Tell him/her you weren't sure what your immidiate boss was talking about. So all you did was listening. After all, he WAS YOUR BOSS, how were you supposed to know what to say, or what to do? They will understand. Go out get a date, or get drunk,have a good time, and stop worring like a baby.