6 year old worried about dying

For the last few weeks almost every night while he’s going to sleep my 6 year old has been worrying about dying. I’m not sure where it started, it just started randomly one night. He started crying and said “I’m scared I’m going to die tomorrow” and I admittedly did kind of make a big deal about it because I’m superstitious and have had times where I worry about something bad happening and then it happens.

But ever since then I’ve just tried to calm him down, told him he’s safe and healthy and he doesnt need to worry about dying. He says he’s worried about his heart because sometimes it feels fast or slow. I’m even thinking about taking him to the doctor just so the doctor can tell him his heart is perfectly fine. Has anyone else dealt with this? I don’t really know what to do. I feel like he’s having anxiety which I’ve dealt with since I was around his age, I started therapy when I was probably 8 years old. Obviously I don’t want my son to have to deal with anxiety like I have so I don’t want it to be that. Does it sound like he needs therapy?