Hi Patrick...

Don't be alarmed!! This can be totally normal for Pachys...depending on where they came from (warm climate), they could have been outdoors in a greenhouse before they arrived at your doorstep. If they got a chill along the route, they may be going dormant. Bright light (south window) might help them stop the cycle, but short of going outdoors (too cold, probably), there isn't much you can do at this point. As long as the trunk looks good...they will snap out of it when they get to go outside.

Are they wet now? If so, stop watering them....when on their way into dormancy, they don't want any water (NONE)....

Rule of thumb on these guys...if the leaves are yellowing or are gone, don't water them (unless the trunk begins to shrink). Water them after they go outside and have begun to show green again (where the leaves should be).

If you haven't already, I would put them into clay/terra cotta pots...really helps control the moisture.

Hope that helps.