Knowing how you created this would have helped so with no other option I'm going to guess it was hand drawn with a brush of some description.
If that is the case then check the properties of the brush, especially the 'Spacing' setting.....for some annoying reason Adobe decided it was a good idea to have a certain amount of 'spacing' on the default brushes, and furthermore another good idea that you cannot completely remove it.....genius. (And no, unchecking it just makes things worse!...even more genius.)
Despite that, setting this property to its lowest does smooth out the brush considerably...
Regards.
MrToM.