1992 Honda Accord Timing Belt

I had my timing belt changed a few months ago. Today the car stalled on me at a stop light. When I restarted it there is now a high pitched sound coming from the engine compartment. When I popped the hood it sounds like it's coming from the timing belt. I called the mechanic that did the work and he said it might be a pulley.
Is this right or is he trying to avoid honoring the warranty? Also, what could be causing the noise? I haven't driven it again today except to move it to a different parking spot and it makes the noise all the time, cold or hot.