Green netting between van body & high top

I have noticed there is something that looks like green plastic netting in the gutter that runs around the GRP high top part of the van (seems to run the full extent of the high top). I assume this is to filter debris etc from possibly blocking the drain holes? Anyone else noticed this and have any ideas? 

There is a small section where the netting has come out of the gutter slightly. I tried pushing it back in but it seems to have come out again whilst driving (it's not bad, you can only see it really when looking down on the van from a first floor window). It's a 2000 Boxer Harmony.

Smithy

Nothing in mine from new.
During it's life someone has put it in.

PB

Yes you are right PB. 

I called AS service this afternoon and they confirmed that they never put any netting of any sort in the gutter. I've just been out and removed it (now knowing it wasn't original spec) I guess someone put it in to prevent leaves etc getting stuck in the gutter.