Um, somewhat confused

So, the oboe I had from my school was a standard oboe, and for whatever reason, one day it started playing one note, no matter what I played. I changed to a more professional oboe because of that, so I don't have to deal with it anymore. Out of curiosity, what do you think happened? My reed works fine in my new oboe. There were no screws loose and the pads were all on correctly. Any ideas?