Well, my first thought is to mention that you shouldn't get too hung up on the number for any individual test. The meters just aren't that accurate, so what shows up as an 87 could easily be a 77 in reality, and if you start to experience symptoms at that level, that may be all that's going on.
But I've also experienced this feeling of being low when I'm not. What seems to trip it for me is a rapid decline, even if the start point isn't that high and the low point not that low. I was hypoglycemic before I was diabetic, and it sometimes seems like my pancreas can really slam into gear once it decides to do something (you know how sometimes if you're behind someone at a light, and they don't notice it's turned green, and you honk at them, then they take off like their tail's on fire? yeah, that's my pancreas), so I can really come down off a peak in a hurry, and a drop from around 160 to around 100 that occurs over 30 minutes will have me feeling worse than an actual low in the 60 range.