It looks to my eyes to be mite damage... I would spray the bulb and stem with a few spritzes of Schultz's 3in1 spray... it's an insecticide/miticide/fungicide... and follow directions for consecutive treatments.

Nothing to panic about... I've had a few bulbs with this type of damage, too. After treating with the above mentioned spray, the new growth to follow was clear of any damage.

I've used the pump spray indoors, carefully of course, with no ill effects. If you like, isolate the plant in the basement or an empty room, and spray carefully there before returning the plant to the flock... and remember to wash your hands.

None of my bulbs have exhibited further signs of mite damage, so Schultz's 3in1 does appear to work on this. I'm sure there are other mite products that also work, but I like the Schultz's for its multiple uses.

OK thanks! I'll pick some up tomorrow.