"Alien" Question

[nx1701g]

To me it seemed that the crew of the Nostromo thought it was unusual for Ash to be aboard at all.

 

[Teelie]

Ash replaced someone else they knew better so I think they just had a general suspicion of him. Not only was he new to the crew but he acted weird to them. Of course no one knew why he was a little quirky until they discovered his android roots.