There can be many things that can trigger this. First, has she watched something that she can't handle. I found that my second child couldn't handle Scooby Doo when he was younger...it never occurred to me...he is now 10yo and is still that way. He was never able to separate reality and fiction. Second, has her vision been checked recently? I'm near sighted and even I can 'make pictures' with my contacts/glasses not on. It can distort things to look differently from what they really are. Third, little kids can see things that we can't sometimes. I'm not saying that there really is a man/elephant, but I know that some kids can 'see' things. I can give you more than one example, but let me give you one. A friend of ours grandchild, while at church during the service, asked his grandfather, 'how do you get up there, are there stairs?'. Grandpa said no, there is no way, you can get up there. Then the grandchild said, 'then how did they get up there'. Grandpa asked who 'they' were. He pointed and was trying to show them. They were wearing white, etc. This boy was 3yo then and is now 10yo. My husband told me this...I thought it was neat. I can give you another example with a 2 1/2 yo girl, but I think you get the picture.
But, as I said, she may not see anything, but then maybe she does. Have her describe him, does he say anything, is he nice... I know we aren't talking about dreams, but when my two oldest have bad dreams, they want to talk about it. At first, they didn't, but after much coaxing on my part, they found that they feel so much better after they talked about it..fortunately this rarely happens. Perhaps having her talk about it in great detail, she will feel better? Good luck!