my hot water is looking unusually grey

my hot water is looking unusually grey but when i let a glass of it sit a few seconds it goes away.
i understand that hot water has really fine line bubbles that make it appear grey, but this time our water was unusually more noticeably. Could the municipal water source have extra oxygen in it or something different that would only be noticeably in the hot water? is it harmful? what should i do?

Hot water can't hold disolved gas as well as cold water can. If it clears up after sitting and there's no precipitated crud...don't worry about it!