Hi - I'd ask the same questions Infopet did. I'd also ask if she exhibits any signs of separation anxiety but from the description of her schedule that doesn't seem to be a problem.
My first thoughts are that the dog is very lucky and is on a super schedule, you are doing everything very right. She's only 4 months (which don't forget is only 16 weeks) so I'm thinking it's a physical thing and she just can't help it. Definitely don't scold her. I'd suggest that if this keeps up, gradually start adding her toys and favorite things to the crate to crowd it up. If she is aware and can hold it, she will hold it rather than mess up her things. (Needless to say, add washable, bleachable things

This should work with a dog who is basically clean and in a clean environment (which yours is), as long as her body has matured enough to control herself.
Good luck and keep us posted,
Brenda