I can ignore Hoku's whining and crying (she did that while adjusting to her crate and her playpen) but she literally screams in the x-pen if she knows I've left the house

I actually stood outside smoking a cig the other morning and waited to make sure she stopped screaming. Came home a couple hours later and she was a wreck, not screaming but crying, trembling and whimpering. I calmed her down, fed her and an hour later put her in her crate and she was fine. Maybe because of her heart condition I just feel that there's no reason for her to ever be 'that' upset. Am I wrong