She noticed another person who was intensely aware of Galt’s presence: Hugh Akston glanced up at him once in a while, involuntarily, almost surreptitiously, as if struggling not to confess the loneliness of a long separation.
She noticed the occasional, surreptitious glances that people were throwing in their direction.
Cherryl unlocked the door and slipped in quietly, almost surreptitiously, as if hoping not to be seen or to see the place which was her home.
The rest of them were trying to do it surreptitiously, each attempting to catch a glimpse of the others without letting them catch his own glance.
There are no more uses of "surreptitious" in the book.