@Calvin, correct (my mind was a bit off while typing the message)
Also, when we first found out that SNDS is listing trap hits in a specific period of time we tried to pinpoint hem.
All effort was useless, I assume they will bounce or generate a feedbackloop (if you are subscribed in the JMRP).
Though if it ever was a user causing the feedbackloop or automated system, you never know.
With the natural proces of adding customers a spamtrap can be triggered from time to time, as long as your bounce management is acting properly having 1 or 2 in a while can never cause problems.