Hi Mike, thanks for your help. 

Optimizing straights in revit has no effect on the issue. We are using "auto" length when straight length = standard length for the part. 

Here's a few things we've determined since this post. 

The fabrication part has this issue when a tap is connected (Revit connected), I'm not sure of other conditions that causes this. 

If we remove the database setting value for the "straight" in the connectors for the part, the issue goes away.

Disconnecting the tap from the straight in Revit, and exporting MAJ's also resolves the issue. 

The length added to the straight piece resulting in the error is 2x the "straight" value for the connectors on the part (TDF/TDC) in our testing. If the value is set to 0.875, we get an additional 1.5" added to the seam length of the part when developed. I've attached some photos to illustrate the difference when the straight value is modified.