Put simply, any time you file a claim, there is usually a rate increase. Since you don't know who it is that hit
you, you would have to go through your own coverage. Glass claims fall under a comprehensive
claim, which tends to be small. However, even small claims can lead to a rate increase.
I recommend getting an estimate for the new side mirror prior to filing a claim. Furthermore, unless you have specific glass coverage (which would give you a lower deductible), the value of damage must exceed your deductible prior to insurance providing compensation. A side mirror claim might not exceed a standard comprehensive deductible.
This decision is ultimately yours. Best of luck, and if you have any questions don't hesitate to ask