Mysterious doubling R.I. State quarter

I saved this from circulation 22July15 but found some odd doubling about 4 days ago. It's a 2001-D Rhode Island State quarter with doubling under the bridge in 4 places. Since single-squeeze die production kinda eliminated classic doubling I was surprised to see this because it really shouldn't be there:







Here's a better pic of the left span...



So is this some kind of design creep or die stutter? Anyone know what this really is? Any help would be appreciated...Spark.

 

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It's been raining and that is excess water running off the bridge.

 

It looks like a worn die to me.

 

My guess is that it is a trail lines. Often happens in the polishing of the dies.

https://www.error-ref.com/?s=Trail+die+

 

After reviewing the section on die trails at error-ref, this seems to make the most sense. Big thanks to @Pickin and Grinin . And thanks to all who responded, nice to be funny and great support all around. It really does look like rain draining off the bridge @Neal

What sold me was the info about the polishing bristles being forced together by design elements, and the pictures of examples showing the parallel effect on the polishing lines.

I had read the info on die trails maybe 6 years ago, but I didn’t realize how pronounced they could end up being. Mystery solved…Spark