You did the right thing, but it's not so much an equipment question, as a matter of what YOU'RE comfortable with.
Take this to your grave: If you are not satisfied that the dive you're about to make is safe -- and this includes buddies, equipment, weather, etc. -- don't do it. If you are worried about appearances or insulting a potential dive buddy by having to tell him you think his rig is unsafe, use a little diplomacy, or feign sickness. Just tell 'im you pulled a muscle or developed a horrible pain in the gut ("Where is the nearest head, dammit? Must've been last night's fish!"). Later, at the bar or over the grill, you can discuss equipment philosophies.
The presence of an octo doesn't necessarily make a given dive (or buddy) is safe, just as its absence doesn't mean things are unsafe. You have to decide that for yourself and it's hard for a novice diver to do that.
Be honest with yourself and assess your capabilities. They will constantly grow over time and as they do you'll be in a better position to make informed calls.
Best regards
Doc