Yes, I would say 4,392 could very well be right. Easy to check though. Check it, write it down, and recheck the next day, week, or end of TV watching night, whatever, to see the change. Then you will know for sure.
If you have four years on it, you (1,098/yr) are right about at the same burn rate as me at 1,052 in year one. I have heard bulb life quotes like you mentioned at 3 yrs or so. Huge variations by # of hours watched and if you have unknowingly left the bulb brightness set at the brightest setting set at the factory. First thing to do is turn bulb brightness down. (to 'Natural' on Mitsub. which approximates 6500 kelvin. Not 'brilliant' or 'bright')
From what I read bulb hour quotes ranged from 3,000 In 'torch mode' (brightest setting) to 4,000 6,000 7,000 bulb hours. The amount of on/offs affects the bulb life too. One guy who had a Misub. DLP in a some kind of a hospital ward room or something similar said that TV was literally on 24/7 for a full year. He said MAYBE it had been turned off once or twice in the whole year. I don't recall if the bulb was still going (I think so), or if that is when he replaced the bulb. But after just over a year the TV had 10,000 hours on it. I do not think he was BS'ing. So with normal on/offing I am guessing 4,000 hrs conservatively for me.
