When exporting an ID covet page to PDF (PDF/X-1a), we continue to get very small while lines around the objects. I've removed any strokes from our objects and have no printer marks or bleed selected. The lines are very very faint, and barely noticeable unless zoomed in tightly.
Tried to select all layers and "merge layers", but that option was not available.
Those are stitching artifacts due to flattening. Why are you using such an archaic format for PDF?
The recommended standard is PDF/X-4 for any modern workflow.
The PDF/X-1a is the export format my EinC wants, and he's currently out of town. I recommended X-4, but we were still getting the artifacts when exporting "fast web view."
Exported as PDF/X-4, received compatibility error for Acrobat 1.7, so selected compatibility with 1.5 and it appears to have done the trick!