What type of steroids did you take? How long? Did you get any gains from it?
When gyno will show up during a cycle is dependant on a lot of variables; type of steroids, amount, length on, etc. Most of the time they DO show up when you stop taking the steroids. The reason for this is due to the fact that once you stop your cycle your estrogen levels are usually elevated and your natural testesterone production has already been suppressed for quite some time. This causes a horrmone imbalance (low test high estrogen) which results in the moobs. More experienced users of anabolics take other compunds throughout the cycle which keeps their estrogoen level low (nolvadex, arimidex, aromasin, etc) and upon conluding the cycle will do a proper post cycle therapy which restores normal testosterone levels and keeps estrogen levels at their normal levels.
I have seen many unexperienced steroid users get gyno and other sides because they did not know what they were doing. As well, I['ve seen many experienced guys go through full cycles, get no sides, and maintain most of their gains. There are many factors involved however, including genetics, general health etc.
If I were you, i would make an appointment with yoiur DR. to get the appropriate blood tests to check your hormone levels. If you truly did a cycle of steroids and have not recovered properly (normal test levels etc) you could expect more problems than just the gyn.