Can I reverse this minor decay in my tooth?!

Can I reverse this minor decay in my tooth?

I had my regular checkup yesterday, and as the hygenist was checking for cavities, she found one spot that she thought was just barely sticking, indicating that it could be decay. She wasn't sure, and said that it could just be sticking in the groove a bit. Also nothing showed up on the xray that was just taken. The dentist then looked at it and decided that it should be filled "just to be safe," and that it is a "very small spot."

I've been researching a bit, and it sounds like there is a chance that the decay could be reversed by using flouride as long as it isn't past the enamel. Judging by what they had to say, I'm guessing this isn't past the enamel. Would the explorer (pokey metal thing) actually stick in the tooth if the decay is only in the enamel? It just barely stuck at all.

I'm a little fussy about this, since I haven't had a new filling in probably 15 years (had an old one redone recently) and brush and floss religiously. I really don't want another filling.

yes, an explorer would stick in the tooth if the decay was only in the enamel, but only if the spot is big enough.
i have several areas on my molars that have deeper grooves, and lots of staining. it's totally natural to have staining in deeper grooves.
anyway, you could have them prescribe you a fluoride toothpaste (about $13.00/tube) and you could use it at night before you go to bed.
or, you could just get some ACT rinse and use it before you go to bed and again in the morning.
this kind of decay that you are describing is called incipient caries. sometimes they can be reversed.
you should talk to your dentist about it. the worst thing that happens is that you go back in 6mos and you need a filling.
good luck!!