A dream I had after my dad passed away

When I was 7 months pregnant with my son; my dad who lived in Mississippi was diagnosed with Kidney cancer. He was 72 but otherwise in very good health. He looked and acted much younger than his age and he was a workaholic, always finding things to do. So, the fact he had cancer was very upseting to say the least. I was in denial and believed he would get better but he did not. He had his kidney removed but it was too late, the cancer had spread. He was in good spirits throughout his illness and made sure his bags were packed to head for Arkansas when I called to tell him the baby was coming and he did just that. He was there to see my first baby be born. I was his only girl so it was extra special for him to see me have a child of my own before he died. He headed back to Miss. the next day. He went through a lot of pain due to the cancer and would try and hide it by trying to sound normal on the phone because he did not want me to worry about him but the last time I talked to him, he could not hide it and he did not want to talk to me sounding like that. He was put in the hospital after having a bad reaction to a pain patch and his wife told me she would have him call me as soon as he was moved into a normal room which would have been the next day; he never called. That evening he passed away from an anyerism(sp?). I was so mad and hurt he did not call me since everyone said he was alert and in a good mood that day. I guessed he wanted to wait until he got home and felt better before he called me. Several weird things happened following my dads death which I know was him letting me know he was around then they stopped. About a month after his death I had a dream about him that upset me. I was somewhere where there was a waiting room of some sort and I saw my dad sitting in a chair talking to someone next to him and I thought to myself "but he is dead, so why is he here?" He looked my way then looked me straight in the eye's with no expression then looked away and continued talking to the person next to him. I was so hurt because he did not even acknowledge me and showed no emotion at all. What if anything could this mean?