Hi, and welcome.
I've not heard of this exactly but you can sometimes get beer up the gas lines, especially if the keg is full and it bubbles up to form a head. So if you had the taps open on the gas lines then there would have been a route through, if the sterilizer was high enough to reach the short/gas dip tube. Also some types of sterilizer can give off fairly pungent vapours and aromas that could have made it through the connecting lines. Also though, people have reported similar tastes through not rinsing steriliser/cleaners out well enough, especially bleach-based ones.
It depends on the potion in question, but many steriliser/cleaners don't keep well when mixed, and/or can attack the stainless if left in prolongued contact with a corny, so it could be worth checking that this is okay in your case.
Cheers
Kev
Corney Keg Back Syphon