The GFI plug in my guest bath is about 3 months old. Yesterday it reset and I noticed that some of my plugs were not working. I hit the test button and the yellow light came on and when I hit reset, the light went off but my other plugs were still "dead". I plugged a lamp into the bottom switch and hit the reset button and everything is now OK. If I unplug the lamp or plug it into the top switch, the other plugs go dead again. The lamp will work on either the top or bottom plug. Is the GFI bad?

Sure sounds as if the GFI is defective. But also sounds as if something funky is going on, so the wiring may need to be checked, plugging in a light at that outlet causes other outlets to be live? Sounds weird.

Who did the work? If an electrician did it, have him come back to check the wiring and repair under warranty.