Originally Posted by
LHSEN
I've read a number of stories on the internet that if this happened once, this will happen almost every time you travel back to the US ...
That is something I would generally consider to be an exaggeration. While for some US persons it may be true for a period of time -- maybe even some years -- eventually it won't happen every time the US person travels back to the US.
Other than agent-selected extra screening, ATS scores are the other primary mean of selecting persons for additional screening; and those ATS scores actually can and do change.