Yeah, I wasn't very clear, but it is unusual for both to go together. What I was suggesting was that the brake light could have been gone for some time, you didn't notice it until the tail light went.
we recently had a similar issue with my wife's car, the right hand head light was blown so we replaced it, just the one, a few months later the left one went, we replaced that and then a few days later the right one went again. If we had waited before replacing the left one she would have had no low beams at all. This can cause unnesscary fault finding, who expects two lights to go together, so you start looking at fuses and wiring and relays, when all along it is two blown globes.
anyway, it is good policy to check regularly, could save someone running into the back of you.