NEVER too old!! It's great that you are enjoying it!! That's the main thing! I'm 44 and started a couple of years ago on guitar and I wish I would have started as a teenager but you can't change the past. Try not to feel intimidated if it takes you a little longer than what is expected for you to learn. So long as you are learning and enjoying!! Music theory and learning an instrument is like learning another language. All the sharps, flats, major, minor etc will be like second nature to you over time. Good Luck!!