Yup, it happens all the time.
As a matter of fact, someone posted the exact same problem not too long ago. I don't remember exactly where, though.
There was
another Q thread for the gals a while back relating to the cycles. This may give you an insight on what's going on.
Anyway, your hormones are going wonkers right now, so you are probably going to be surprised by the regularity/irregularity.