I do, but have never tested it because I first read about it in a Finn Aagaard article where he said he'd tested it and it had no effect on POI. Aagaard's reputation as a person whose word you could bank on was good enough for me.
I even do this in dry weather, ever since I was crawling after a herd of blesbok and realized my muzzle had poked into some dirt.
I also keep a supply of extra tape right behind the muzzle. This is usually good for a question or two at the range. I once told a guy it was to hold the last three inches of barrel in place; he looked like he didn't know whether to believe me, or punch my lights out.
