disembodied

I was on one of the three bridges that cross a local river, each within a few miles of each other. The bridge is very old -- 40's, I think and rocks with wind and seems to support only the weight of three persons. I walked from end to end and back, then heading back to the car, I heard, "bye" from a child's voice. Now ... who said it?

There are two nearly-parallel paths, one in the woods, one out. There were people out in the park, but when I listened for more, I heard no voices at all. I don't believe in ghosts and won't, until one bites me in the arse, but I found it strange. "Bye", by whom? I'll forget about it, until I experience it again. Still, it was worth the eerriness of the moment.