Am I going crazy?!?

My father passed away on 2013. Even now when I hear a noise from his room or where he spend most of the day my mind immediately thinks its him for a slight second. Of course I know he is gone but just the thought that for that minisecond I believe it's him really scares me. I went to the graveyard today to see him and just now, I was on my phone and I'm not sure why but for a slight second my brain thought he was still with us. This really disturbed me and made me feel like I'm loosing it. Is there something wrong with me? 

There's nothing wrong with you Clara you've lost an important person from your life

He's maybe giving u a little visit to let you know he's still with you xxx

There is nothing wrong  with you at all. It so very hard when you lose a loved one and i agree with what katep said.

Parents are the only n bigest supportive ppl in our life,Of course You need time to accpet what happend to you dats why you still think like dat for a secound he is there,dats not about being crazy or sth like dat