Opinions 03 engine swap issue

[Sienne80]

Hey all. I had the bad Castech head issue and turned out the engine was shot. Unfortunately I probably bought it this way two years ago. Anyway I went with a local shop who came recommended to locate and swap the engine for me. 

Used engine came off another Silverado from the same year- probably same Heads I know- with 110k. 

Upon inspection when I got home I’m not liking how the exhaust

manifold is connected to the flange. Picture with the big gap is on the passenger side. Drivers side is ok-ish. 

What would cause this and should I pitch a fit to the mechanic who did this? Should it be something he has to fix? 

Bad motor mount on old engine that made it sit lower?

Thanks for the advice. 

[Mike GMC]

Does it have an exhaust leak?

[Sienne80]

Not throwing any codes yet and I put my hand next to it and didn’t feel any leak but am worried it may start leaking at some point with how far unscrewed the bolts are. 

[muddkatt]

Take it back and let them reseat the exhaust to the manifold and tighten it up.