Bud Sheath Turning Brown?

[OrchidMom424]

Hi everyone!

My paph. acmodontum has what I *think* is a bud sheath coming out from one of the leaves. It is brown at the base/stalk, which I think (on analogy with how my other paphiopedilum looked) is normal. However, I noticed yesterday that the top of the bid sheath is turning brown. I am attaching some pictures. Is this normal? Should I be concerned about an infection or disease? The plant seems healthy otherwise! Any and all information and advice would be very much appreciated! I only had dendrobiums for years and am still learning my way around the paphiopedilum world!

Thank you so much!