Splashing getting water behind liner?

[offtheclock]

Had a lot of people over to help break in the pool yesterday. People started to do alot of cannon balls which was causing water in the deep end to wave over the top of the pool and onto the deck. I noticed later that night after everyone left and I was wiping off some debri on the pool wall that there was some water behind the liner. I was able to use my arm as a squeegee to push the water out but there is still a little.
It was not a lot of water and only felt like it went down 2 ft. Is this normal or should I investigate more? This area was also close to where a skimmer is but definitely where the waves were splashing over. These guys could do some big cannon balls. Kids were impressed. Also is this bad? Thank you!

 

[ajw22]

It is better if you don't get water behind the liner. Over time you can have erosion. I would investigate how the water is getting back there and try and fix it.

 

[offtheclock]

Really think it was from all the horse play and seeping behind. Got in today and it was all gone. Hoping it was just from all the waves.
Please chime in if someone thinks I need to check something else.
Is this ok to happen or should I keep people from making waves?