Mine came off too. I don't think Ruger uses paint on the LCR sights, if they do it doesn't bond well.
XS Sight Systems, Inc. - Products - .22 LR, .22 WMR, .327 Fed Mag, & 9mm
I got one in orange but haven't installed it. I'm not sure that I need to after I painted the factory. SALON PERFECT NAIL LACQUER - TRAFFIC CONE - Walmart.com - Walmart.com