Milk bottles leaking

[donewithitalltodayandxmas]

Dh bought 2 x 6 pt milk bottle from lidl today got one out fridge to use in mash and green lid was tight , opened it and the foil was half opened ( thought was kids as they do this ) used it for tea , all ok
Spoke to kids who said they hadn't had milk and reminded me they were not even here
So opened other bottle to check and all though plastic bit on there was milk in the lid
Is it they are poorly sealed , or is it because we are storing on side ( why i normally don't buy 6 pt)
Would you use this milk or should we just throw in case the seal was broken?
No sign of milk leaking in fridge but only been in there couple of hrs

If it smells ok it will be fine.

I wouldn't worry about this. You would take the seal off anyway when you started to use it and it would be in the fridge for days with just the lid and no seal. It is no different.

I've had this a few times, I've just assumed the lid has pulled the foil off when I've opened it.