By 1999, Aqua advertised their hulls as composite construction aka "no wood, no rot". That's not to say that the day your hull was on the assembly line, the composite pouring material ran out and plywood was substituted.
While we have no idea how common that was, we have been told that in order to "keep the line moving on schedule" that was an accepted practice.
Who really knows for sure until you actually look for yourself.
