I had that as well. I was seriously creeped out by it. The glass felt like it actually lifted up on a cushion of air, a bit like when you try to push two magnets together. There was resistance but it wasn't fully in contact with the table. It moved surprisingly fast as well.
I've had a few spooky experiences as an adult but nothing that actually frightened me, just seriously baffled me and made me feel uneasy/weirded out.
People will just dismiss them as something else though, or say I must have imagined it.
The most memorable one was with my toddler. We started to think he attracted poltergiest activity. We'd hear really heavy bangs on his wooden bedroom floor after he'd gone to bed, like someone had dropped or thrown something heavy.
We'd both rush upstairs thinking he'd fallen out of bed, or that he had woken up and was playing and had pulled over some furniture or something. When we got there he was sound asleep in bed with nothing on the floor, no signs of any disturbance. So weird.
That happened a couple of times when he was really young, but big enough to be out of a cot.
Also in the same house, I was once in the kitchen cooking dinner waiting for DH to come in from work and the (quite little) DC were in the next room watching TV. I heard the front door open, then close. Usually he'd stick his head round the door to say hello before going upstairs to change, but I heard footsteps going straight up the stairs so I assumed he needed the loo. Ten mins went by so I went upstairs and there was no sign of him. I asked the kids if they'd seen him and they said no. Asked them if they'd been out by the front door for any reason. No. He wasn't even home. He came in about 20 minutes later.
Also the same house, DC was at nursery and I was in the kitchen one lunchtime. There was a breakfast room off the kitchen and suddenly I heard, very clearly, the sound of a small child's voice coming from in there, saying 'Mummy' and something else indistinct that I couldn't make out. I immediately rushed in there, really confused because my DC was at nursery and...absolutely nothing.
I had a few experiences in that kitchen where I would be standing at the worktop doing something and I'd suddenly get a really strong sense that someone was standing right behind me, really close. Of course I'd swing round and there was never anyone there.
I don't take much interest in anything woo or paranormal really, it's not like I am always on the lookout for it and I accept there is usually a logical explanation for these things but I'll be darned if I know what it is.