Scope: Visible in both TSRE and Open Rails.
Example images:
In TSRE with tile line display turned on:

Number of downloads: 19
In TSRE with tile line display turned off (click on image to see this full size):

Number of downloads: 23
Close up in TSRE:

Number of downloads: 18
All 4 tiles you see here were painted with the same texture art. I don't recall if they were all painted at the same time or at different times.
There is a possibility it's a microtex problem... does TSRE use the microtex file?