I certainly couldn't say it's NOT a virus Gerd, but can't confirm it is either. I mention this because I know that sometimes - and especially with Narcissus - if the leaves have been exposed to light at below ground/potted level (say you tip the pot over, or weed around the bulbs) when the leaves grow to above ground or potting level, there will often be a pale, even lemon coloured band where the previous exposure was. If you see what I mean. But this pale in your pic doesn't look quite as definite as that. It's usually more a pale stripe.