Ya know, this is something that I don't think is widely done yet the markings left behind seems like they would offer great insight to the outcome for the reasons of the candle burning.
I have gazed upon the glass as well and wondered what the strange shapes I have viewed could mean. Usually I saw streaking down the sides that would somehow indicates the speed in which the working would reach manifestation.
Depending on why you have burnt the candle...was it for a job? Or healing? I don't think the divination meanings would be universal. Different ideas for the same symbol depending on the work. For instance if the candle was for healing of a male friend, then an old man might suggest he will live to be old, if it was for a job then maybe an old man is who you will work for or will somehow guide you to the job .
Since your candle changed perspectives I wonder if a couple might be involved? Brother sister? Or sex change? Genderfluid? God/ Goddess blended as one? So depending why you were burning the candle it may give you more to ponder while you gaze upon the glass.
Great question by the way.
...I would be interested to know if this practice has a name.