I think the reason why he was sweaty, and out of breath was because he had a brush with death, and the first one in a long time. He's still terrified of death even as an immortal Endless, and the destruction of his memory terminal reminded him he can still die.

As to where he escaped to, and why an Acsian can interact with him is a mystery. They could be anywhere. A thing to note is that Calyx had audible footsteps in this space, and the Ascian did not.