Certainly check the level of the steering fluid. Unfortunately, checking the fluid isn't adequately included in regular BMW maintenance procedures, and there is no convenient way to drain and refill the system (as with the engine oil, for example). Nonetheless, you shouldn't ignore it. Get yourself some fresh fluid and a turkey baster, then reach down and unscrew the top of the reservoir, and suck out as much of the (probably very murky) fluid as you can. Replace with fresh stuff, to the indicated line (you're probably well below that now). Since you've got a 14-year old car, this would also be a time to check on the condition of the power steering lines and replace them if they're worn and weeping fluid. This would also be the occasion to flush the entire system and have entirely new fluid in it.