Paph newbie help! Is it rotting?

[Kim in CT]

I purchased my first paph in March and repotted to S/H in April (Paphiopedilum philipinense x (roths. 'Jungle Selected' x roths. 'Atlantis' SM/TPS). It has lost one of its lower leaves and looks to be losing another. Is it sick? or is this a normal transition thing? It's been growing inside, bright indirect light, ~50% humidity and 60-70 degrees F and I'm getting ready to transition all of my orchids to grow outside for the summer. What should I do to help my paph survive? Is it rotting? I'm hesitant to disturb it until I hear from more experienced growers. Advice please?