My first suggestion is to upgrade to 0.9.4 (released about a month ago), the fix may or may not have made it in to there. If it still occurs then you need to report it as a bug on github here:
as a bug because it won’t be tracked (and may not be noticed) here in the forums. From a quick look, this fix may have made it in to the 0.9.4 release or it may not, as it appears to have perhaps have been merged as part of the major gerber rewrite which got backed out about 2 years ago (as parts of it were broken.) Unfortunately the folks who did that commit appear to have given up on Fritzing possibly because development and releases had died, and did not respond to requests for help to fix the code, so it got backed out. Development is trying to restart so there is some hope that this may get fixed if it is reported. It is possible this specific fix can be integrated independently of the larger fix (since it looked to be separate) if reported.
Peter