Good job on 10 years sober!
Sadly addicts lie and minimize. And for what ever reason many don't consider pot a drug like cocaine. Pot is not the harmless drug or substitute many want to think it is and has other issues besides heart problems. And I've witnessed pot not mellow people out and put them in a nasty mood.
I just saw some study results on pot which include increased stroke risk.
https://www.webmd.com/stroke/news/20...curring-stroke
If he was using pot he might have laced it with something or given something he didn't know was in it. And previous drug abuse has cumulative side effects that don't show up right away.
Hopefully it was just nature. Stay healthy yourself
Good Luck