Carby, chunk of metal missing??

so my new FMF muffler arrived today. bike ran ok, but not that well so took the carby off the bike and while re-jetting and moving the needle clip down a notch, i noticed a chunk of metal missing from the carby housing near the throttle slide...(red circles in the pictures). no idea how it got there...maybe someone else could chime in on that?

wondering if this will cause any future problems? such as leaks or letting dust in??
(sorry if its a stupid question). just wanting to make sure.

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Yeah I know it won't affect the operation of it.
I gave it a good clean out anyway to make sure nothing was in it.
How bout dust getting in though...higher chance of that?
 
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