To be perfectly honest, I would much rather that my bezel was a bit too small than a bit too big.
If your bezel is too big then your stone cannot be set securely. It is likely to be untidy at best, and at worst the stone will wobbly about and could eventually come loose. To sort out a bezel that's too big you have to cut it open at the solder join, re-file the ends to create a tightly fitting join, solder, file again. You get the idea - it's possible but it means repeating your hard work, and sometimes it's just easier to see if you've got a smaller stone to fit in there instead!
However, making bezel a bit bigger much easier.... I make my bezel settings bigger by stretching them. This works with fine silver, sterling silver, all purities of gold and even with copper, although the softer the metal you have used to make your bezel the easier and quicker the stretching will be.