black spot on catt - is it doomed?

[grasshopper]

This catt is potted in s/h and grew 2 new pbulbs last summer. I try very hard not to splash water on the pbulbs when I water, but I noticed today these black spots on one of the pbulbs. I had not peeled off the papery sheath from the pbulb, which someone told me is a good idea to do since they absorb the water and can lead to rot. (I peeled it off today when I noticed the black spots.) What are your thoughts? Rot? Something worse? Currently, it's only affecting this one pbulb, but there is a spot on the leaf on the adjacent pbulb. What should I do?