I had that same thing almost happen on my 97 vortec 5.7 in my truck . I was going to run comp cams extreme rollers . Had it all set up and was turning engine over on stand and heard a click . Saw the outer edges of the self aling slot hitting retainer . Switched to cranes ultra gold race ones and it didn't . I don't know if some rockers go down a tad more than others or if some retainers set up taller . Don't think I answered your question but I do know what your talking about .
Don
Don