Is this root rot on my Phalaenopsis?

[Pupsicle]

Hi all,

Longtime listener, first time caller. I'm fairly new to orchids and so far have not had any major problems to deal with. (Thanks in part to this forum!) However, my sister-in-law, the chronic overwaterer, gave me a beautiful Phal for Christmas, and I believe it may be experiencing the first signs of root rot.

When I checked on the plants today, this one Phal was really wet, while all of my other plants were dry. (I haven't watered it since bringing it home on the 25th -- five days ago.) I managed to get it out of its pot to look at the roots, and some of them are starting to go black and mushy.

Like I said, I've not yet had to deal with orchid trauma, so I'm not really sure what to do. I don't want to be overly fussy about it, but if I do need to address the roots, please advise.

Also, the plant is potted in lots of sphagum and the roots/moss are very compacted. I would be tempted to repot it in something lighter, but it's in full bloom (two stems!).

Thanks for any advice you folks may have, and thanks for all that you've already unknowingly given.