Comp Cams not responding

I saw 2 comp cam roller cams for small block chevy break just befpre the dist gear, lucky for them all the valves kepy moving, 358 DIRT MOD They must have a run of bad cores, new cam at beginning of dirt season. I have a new roller for my big block mopar not in motor yet but I bought it in the early spring. Motor man says he never has had a broken cam until a few weeks ago 2 in 2 weeks, comp knows about it but did not say much.