Opened my right saddle bag this morning to grab the liners for my riding gear (getting cold in the mornings), and 2 screws fell down into the lid. Looked around and quickly discovered they were 2 of the 8 that hold the latch assembly to the bag. They look like a stainless screw, with a Phillips head and a soft rubber washer.
Might be prudent to check yours, next time you go into the side cases.