Thanks for sharing about pollination groups, Mike! I never knew they were categorized like that. I did a quick search, and supposedly Honeycrisp is G4, and Fuji is G3 or G4 (I'm finding mixed results - possibly due to different varieties of Fuji), so that's good.
Bear in mind that, in addition to what others said above, other things can affect blossom time - yearly fluctuation of weather (spring arriving earlier, for example), as well as microclimates around your trees (e.g. one may have nice rocks nearby that stabilize the temperature of the ground better, or be nestled in a dip in the
land that holds in cold air, or is closer to your warm house, or is in the shade of your house, etc...). Watching over several years may show a different result. You're probably fine.
But if you think you need a third tree, you absolutely do - and a 4th, and a 5th, and however much you have space for. =P
I have three Honeycrisps (from two different suppliers) and a "Fuji" and a "Red Fuji" - they haven't blossomed yet this spring, but will in about 15-30 days. If you like, I'll pay attention and record the dates they each begin and end their blooming and report it here. Mine are still young-ish, some in slightly shady areas, some in full sun, and most in an dip in the ground that traps cool air, so it won't perfectly reflect your situation, but if it gives you peace of mind I could see how solidly their bloomings overlaps.
I really wouldn't sweat it though, many sites seem to *recommend* Fuji to pollinate Honeycrisp, or Honeycrisp to pollinate Fuji, so you're most likely fine. I'd give it a year or so, and see what happens.