Periods can be late at times...besides its not that late yet.
And unless you had an actual intercourse there's nothing to worry.
In case of intercourse (his penis in your vagina), there might be a chance.
Anyway, its just been 30 days if I am right...wait till it at least 40 days..and if you've still not got your periods, take a test. Those are quite easy to use and decipher.
Take care.