There're all kinds of "fixes" for this problem. IMO, this is the easiest one:
There's a cover just inside the trunk - 5 screws gets it off - that exposes the latch mechanism. Wiggle the left bag lever and find it in the mechanism. You'll see a rod and a green plastic holder flopping around - that's bad. They're supposed to be together like the others. Put them back together and get a very small zip tie and tie them together. This is NOT a permanant fix. You'll still have to be more careful opening the left side than the right. There are variations of this fix and other completely different fixes - I'm sure others will chime in.
There is also a rod inside the bag itself that can be adjusted. I did this also and my bag is pretty easy to open now. That adjustment is much more complicated. Here's a link that explains it - not the greatest directions but usefull none-the-less. http://www.1800goldwing.com/Saddlebag.htm