Dentist/or dental student question..brown stain between two upper front teeth?

Ok it's a dark brown stain and I'm going to make an appointment because for awhile I wasn't on my mother's dental plan (got taken off dads) and I was only making enough payments for my car which were about $400/month at the time, so I couldn't really afford a dental cleaning because I wasn't making enough to reimburse the amount that would be deduced from my bank account. So I have been for awhile..late summer, so starting from that time (because I was overdue for a cleaning the last time, which at that point I wasn't on a plan) it's been six months, I know, procrastination not good..been 3 months since my sis went in so she's on my moms plan and isn't in school (i am now) so poor excuse for not going sooner but I had to be sure considering that extra cash taken out for it would have been double with the car payments, which that amount included insurance. So, anyway, the real question is is it a stain? Like I read online it could be from coffee tea, which I drink, but I floss, brush, and use mouth wash everyday (faithfully), so plaque couldn't have accumulated that much, unless it's the hard stuff, but I do floss and brush. I'm pretty anal about teeth now (took me long enough to be since I didn't care as a child) because I absolutely hate the drills and I wear a retainer because I had braces but this stain appeared a short time ago, sometime in mid to late december. Or rather I noticed it out of the blue, so can anyone that knows about this can help? I'd like to set this worry aside now before calling. Also, I know it looks like something is stuck there but isn't, trust me, flossed, picked at it, looked in a mirror, it's a stain. But there is no pain whatsoever. Can anyone help?
--------------------
Since you state your hygiene is very good, I seriously doubt it's a cavity. I would guess it's just a stain, just like you thought. How did you get it ... probably the tea and coffee. I have patients with very good oral hygiene and they still sometimes get stains. Please don't worry, a quick polishing will remove the stain and your back in business. I have seen teeth stain even though there is very little plaque. I'm not aware of any method you could use at home to remove the stain. Some one will probably tell you to buy an over the counter dental instrument and remove it yourself, BAD idea. If you haven't had a cleaning in a long time, it may be time to get one. Even the best brushers still leave a little plaque that can only be removed by your friendly hygienist! Dr. Dan Update: No, you might not have any sensitivity with this type of decay (if it was). This are sneaky little cavities and are often only seen on radiographs (x-rays). So short answer, it may never "hurt" and you might never see anything other than a "weird" color change. With your history, relax, just a stain!
Source