Rear sight issue - Meprolight Night Sights for HK Pistols and Handguns

I have had an H&K P2000SK for about 7-8 years and I purchased it brand new with Meprolite night sights. I wear the handgun daily and have not had any issues until now. My sights barely glow and my entire rear sight fell off and it will not hold any longer. I have dropped my handgun in the past a few times and it suffered a little nick a few years ago but it showed no signs of damage. I called H&K and they did not meet any type of warranty since the handgun had been purchased quite a few years ago. So, I ordered Meprolite night sights once again because that is what the H&K rep suggested. I love my H&K and will give Meprolite another opportunity. I don't know whether other brands are any better or worse. But obviously I still trust them to do it all over again. I just wished they lasted longer.