The only time I have memories crop up is for stuff I haven't 'integrated', 'resolved' or 'healed'. Your brain will bring it (unprocessed stuff) to your attention by resurfacing the memory - acknowledge me it says! Memories are triggered because there is an association with what is happening 'presently'. I view it as an opportunity so I thank my mind for those memories. It will also cause some form of emotional response (annoyance, fear, disinterest...something) when the memory arises. I just allow the memories to play out without judging them - you witness the memories with no attachments. For the most part my head is completely empty, unless I decide to talk to myself of course , and that's why I am able to notice and identify my triggers quite quickly. I'm able to manage those triggers for the most part. Well, that's been my experience of it anyways. You brain doesn't sound too odd to me