I never complain about having a bit more reputation point, but today somehow I get 5 upvote
for answer I made in a very short term and I feel myself like not deserving those points.
Could that kind of behavior could be avoided by some kind of moderation automated process?
In the help center entry on reputation you can find:
You can earn a maximum of 200 reputation per day from any combination of the activities below. Only bounty awards and accepted answers are not subject to the daily reputation limit.
so the moderation is taken care of.
If different questions are upvoted in short succession it could come from a single admirer who was pleased with one answer and looked at some others and decided your effort was valuable. The StackExchange system keeps track of such things and when upvotes excessively originate from one source (I don't have exact numbers for that) upvotes can be nullified and their reputation voided.