Phal. puzzler (at least for me!)

[caseydoll]

About a month ago I purchased a phal hybrid off ebay. Its from a reputable seller that others on here have bought from and were happy with. It was very healthy when I got it and had 2 spikes and 3 healthy green leaves. No sign of rot or pests. It was in sphagnum moss but the moss didn't look old or compacted. I noticed that after about 2 weeks that the lower leaves were turning slightly yellow. I repotted it and it had very healthy roots. The next week both bottom leaves turned completely yellow and fell right off. That left 1 leaf. (of course I cut the spikes off). Today when I came home from work it had NO leaf and the completely green leaf was laying on the ground. Like I said, there is no rot at all going on and I haven't had it long enough to kill it!

And this exact thing happened to me with another very healthy phal I bought from the same vendor at the beginning of summer. Same exact scenerio.

Any ideas on why this would happen? I have had phals for about 10 years now and have never had this happen before. And back in the day I totally abused the poor things due to lack of knowledge. I would LOVE to hear others opinions because I am stumped! Also, will it grow back or should I toss it? The first one that did that is still leafless with nothing new going on.