I heard from some of my friends which also adsense publishers said that big G will deny the cashout for certain publishers when the publishers reach the payout limit which is USD 100 for reason there is some invalid clicks occur in the way to get the amount of USD 100. Is it happened before to some of you?
Yes, Google banning people after they reach at $100 limit but it will effect only who is doing wrong publishing method and who is working as against adsense TOS
It probably depends on fast you hit the $100 limit. If it was in your first month and unusually quick they may take an extra look at it. But if it was over a period of months I would assume if Google suspected something they would have already acted. Like leandar said, if you have been following Google's TOS you have nothing to worry about.