Completely random - ran over a client like say Osbuddy or official rs client?
how random we talking here because it doesn't sound that random to me, random enough to be unbannable would be a completely random interval between x-x
they either picked up a pattern in the shit you were setting (maybe setting the same intervals 2 frequently without noticing, or a stupid crazy amount of hours which is not humanly possible)
Also if what you say is true and you lasted over 1000 hours, not doubting you here. Then your account would have been monitored a while.
Hope that helps.