I just pulled my tank and took a look at my o-ring. It did not look pinched at all. So, I pulled it out to examine it and compare it to the replacement I purchased to see if there was any visible pinching damage.
'Pinching' doesn't quite mean what most of us are probably thinking in this case. Instead, there are some small tabs on the o-ring and when you install it those tabs need to push into the fuel pump housing, if they don't then they stick out above it. The groove is small and the tabs are too so when re-installing you need to just take time to make sure the tabs are flat and into the groove and not sticking up.
I can also see how you might have one pinched that may never leak, it's such a small part of the o-ring and I think you'd need a couple tabs out of the groove before it would leak - just guessing here, I have no experience.
Anyway, I reinstalled my old one and put gas in it, no leaking. I'll take a couple rides this week to make sure I didn't add any leaks.. LOL fingers crossed.