Lower notes are harder to play on many wind instruments, especially the larger ones. The lower notes require slow, warm air. Also I found when I was starting on tenor that my ring finger would slightly uncover its hole without me realising it, making the lower notes not sound properly. Because tenors are longer than soprano and alto, the fingers are spread apart more, and when our pinky finger moves, the ring and middle fingers tend to move too, so we have to be extra careful their relevant holes are covered.
You don't stop playing when you get old. You get old when you stop playing.