You are correct it is probably the stress of the transplant that has triggered the plant to shed the oldest of the leaves. Palms often shed old fronds.
The best thing you can do is remove the yellow frond. The tree no longer has any use for it. That is why it is letting it go.
There is one more explanation that the new pot is not draining correctly. Perhaps the hole got plugged while planting. If the palm is sitting in wet soil that stress will also trigger the response to shed the outer fronds.
If it is transplant shock, there is nothing you can do, but take good care of it and let it run its course. The course in this case, shedding of the oldest fronds. There is a good chance the palm was going to do this in the next few months anyway, so the transplant just triggered the response earlier. The only thing other than normal care you can do is make sure the hole is not clogged. Did water run through after the first watering?
If you live in the Southern Hemisphere or on a tropical island you can go ahead and fertilise the plant with a transplant fertiliser. If you are in the N. Hemisphere hold off on any fertiliser until spring. At that point give it a palm or citrus fertiliser. If you can not find a palm fertiliser in spring. Make sure you use a fertiliser with magnesium and iron. If you can not find a palm fertiliser you can also give it a little bit of Epsom Salts in the spring. This is magnesium sulphate. Palm trees need a lot of magnesium. Without it they can not take up nutrients like iron.