Yes that's a big difference and it could be a problem. It shows that there's not enough voltage across the resistor.
Imagine it like this. Your LEDs are books that you need to pack side by side into a wooden box. Each book is a slightly different thickness (different forward voltages) because of manufacturing process variations, and their thickness will also vary with temperature. So you use a piece of foam at the end, to take up the remaining space, so that the books will be held fairly tightly regardless of variations in their thickness. That foam is the series resistor, and the width of the box is your power supply voltage.
A resistance of 1 ohm corresponds to a very thin piece of foam. If the thicknesses of the books varies significantly, you'll get a big variation in the force that the foam creates (the current, in this analogy). But if you take out one or two books and use a fat piece of foam, variations in the books won't make much difference to the force. That's what you want.
Now there are two possible reasons for your problem:
(1) There is only one LED and its forward voltage is too close to the power supply voltage - in the analogy, you have only one book, and it's almost as fat as the box, so there's not much room for the foam. The only thing you can do here is to increase the power supply voltage (use a wider box) so you can use a fatter piece of foam.
(2) The calculation software has put too many LEDs in each series chain - in the analogy, there are too many books side by side and there's not enough room for a proper piece of foam. In this case, you need to remove a book - possibly more than one - so there's a wider gap for the foam. Then you can use a fatter piece of foam that will absorb the variations in book thickness (LED forward voltage) without causing large changes in current (tightness of the books inside the box).
This is NOT a perfect analogy. For one thing, using a fatter piece of foam will increase the tightness of the packing, whereas using a higher resistance will decrease the current. It's just to get across the basic idea.