Yeahjust bad acting. Binge watching and almost didn't make it to second episode. By third episode realized Hiddleston was the annoyance.

I really enjoyed this little quirk of Hiddleston's performance. I think it endeared him to Roper, and made him seem pliable, a protg to be nurtured in the ways of the world; but it was also an ingenious method of subterfuge. I felt there were so many gradations in his laughs and smiles: they ranged and flickered from genuine, abashed amusement to subtle contempt and everything in between. It was part of that chameleon charm he had, ingratiating, blending in; but if you look deeper, really sense the tenor of a scene, the smiles and laughs can often be freighted with a tension or lightly veil some cryptic emotion.

Hated it too. Just bad acting.

His smile/laugh before he went undercover was different. His undercover laugh came off natural and added to his charm as Andrew Birch to make one feel comfortable around him.

I actually thought it was great acting. A normal human being laughs and smiles nervously many times a day. We are so used to se Bourne-like stone faces types on film that we perceive that behavior as natural. I thought his smiling/laughing was a great nod to the fact that he is not a trained spy. It made the performance much more believable and natural. It felt forced, yes, but the kind of forced a nervous person a bit out of his element would display. Great acting on Tom Hiddleston's part IMO.

I thought it was done on purpose. Pine is trying to convince Roper that he's just a guy out of his element in Roper's world. I thought the laugh was a nervous laugh that he was doing on purpose to show Roper he isn't some James Bond type who can be totally cool in any situation.
When he became Andrew Birch and Roper had him practice signing his name. He laughed while writing this name. I thought that was Pine putting on an act for Roper that he was really enjoying this and excited about getting this company.
On the flip side, i also thought it was great acting on Pine's part when he was yelling at Roper over the passport. He supposedly didn't know who Roper was or that he was a scary, ruthless criminal I thought it was a good way to put Roper off helping to hide the fact that Pine knew exactly who he was dealing with. He even called Corky Roper's "little friend." Pine was aware that Corky was also a dangerous man, but hid that fact by insulting him.
Fraaaank. FRANK! Get my jean bin. Susie wants my jeans.
No she doesnt.