They may not pull you over just for the missing light to ticket you for that, but they will sometimes use it as probable cause if they suspect (or just want to check) you for something else. It is a mistake to drive with any lights out for this reason. Lots of minimum DUI and drug busts happen that way. You don't even have to be driving erratically, but it gives the officer an opportunity to get close enough for a sniff. With the legal BAC limit at .08 in most states now, it doesn't take much to get in trouble. I would make sure that anything as easy to spot as that high brake light is working properly.