Flaked Maize, Rice, Wheat, Barley, etc... has gone through a pre-gelatanization process whereby the starches are broken down to a lower molecular weight. Therefore you don't have to conduct what's called a cereal mash, instead you can just put these in your normal mash.
Steeping these adjuncts may be ok (though less effective) if you added that steeped wort back to the mash tun for a period of time or if you steeped in your strike/sparge water (you want those starches in contact with enzymes!).
Generally speaking adjuncts need more enzymes to convert and if you cereal mash them you would normally do so with some 6 row barley because of the high diastatic power.
Next time, just remember to mash the flaked adjunt with the rest of your grains.
Did you screw up? RDWHAHB! I'm sure you released some of the starches from the steeped adjunt into the mash water and as long as that mash water came into contact with enzymatic mash water you should be ok.
Time will tell friend. Let us know how it turns out.