My pleasure - sort of.

It was my RHS that fell out too.
When I was fitting my clear lenses (the RHS one of which fell off) I noticed that the fixing screws were different on both rear blinkers and assumed the previous owner had lost and scrounged different ones. I was also (maybe too) careful of not over-tightening the screws as I tend to be a bolt shearer and have cracked plastic blinker lens in the past. Maybe a dab of Loctite thread glue would be the best idea.
The identical 2nd hand Bonneville unit I bought yesterday also had different screws each side of the lens. The inner one was a long fine threaded flat tipped version and the outer was a shorter coarse thread tapered screw tip one. When refitting the lens I found that they may have been original as the shorter coarse threaded one would not engage the inside body hole.
What did you find with your screws
@sonny ? And can anyone else chime in on the screws in their blinkers. I can see how using the wrong screws could increase the chance of them falling out.