Do memories ever just wander through your consciousness unexpected?

Tonight my mind unexpectedly replayed a memory from February 2005. I went to Washington D.C. with my best friend. We visited a number of meaningful memorials, among them the National Law Enforcement Officers Memorial. We found the names of his 37 comrades that died on one day. They were grouped together. Some of those names represented close friends that he still misses very much. I respect his privacy too much to detail the moments that linger in my memory. I just wanted to say that the visit touched me and I’m glad I was there.