For future reference or anyone who is interested:
Voting your own post or comment is perfectly ok.
If it was not ok, anyone could just create a second account and then vote their own account.
All a prohibition on selfvotes would do: People who want to cheat, would just get a second account and those who play by the rules would lose out.
It would be a rule that could not be enforced equally and thus would be a stupid rule.
Without KYC type of account registration (which I certainly do not want) there is no way to tell, who owns which account.
TL;DR: selfvotes will always be possible anyways because sybill attack, so don't punish those who play with open cards.