A ghost gave me a bunch of caps in Fallout Shelter?

Okay so I was just doing my thing playing Fallout Shelter on my iPhone. I was checking to see how much time it would take for one of my dwellers to level up in the Lounge room. It's only a single room. There was one dweller in there and he was shaking some drinks or something and I trying to touch him but missed and I touched right next to him on the right behind the chair at the bar. And I have no idea what happened but when I touched the space, a dweller faded in the faded right back out in just a few second and I instantly got like 1,000 or more caps. I can't do the same thing again, but IIm wondering what it is. I can't find any info but it definitely looked like an easter egg or something. It was weird and I don't really remember what the ghost dweller looked like because he just faded in then right back out with a huge surge of caps. Does anyone know what this is? IIm excited to find this lol

Its a Easter egg of vault 77