If you curently don’t look like your photo . . . you should update your headshot.
Generally if little has changed in your appearance, your headshot should be good. Now, if you have changed the color of your hair, had a major haircut, gained or lost significant weight, aged a few years, then those are certainly things to consider not confusing your viewer. (the casting or audition personnel)
If you are unsure, start with asking a friend and even a total stranger that doesn’t know you well to look at your photo and ask if it looks like a current photo of you, and to be totally honest. Many times people that are close to you will not notice the changes since they see you all the time. Next, if you already have an agent and you are active, they should have already let you know . . . . it’s time!
In any event, when you leave a casting, give them the headshot that looks as close to you as possible. Explanations do create conversation, but you’d rather those be on the topic of the job at hand.