That is exactly how you should evaluate your training sessions, Mike! Great work. You didn't do what I wanted you to do but..and this is the most important thing: you took what you could from it which is finding somewhat of a base
I hope you are holding the bar in a weightlifter's position and not with a cross grip. If you're using a cross grip you will run into trouble. If you need help trying to establish a clean grip, let me know. This will serve as an excellent time to learn that if you haven't already
It took you only an hour? Dude...most of my Deadlift workouts are 2+ hours.
The thing wiht the HGH/GH levels is that if you sip a protein shake (with dex or mal mixed in) during your workout, you can go on lifting for a long time. The decrease in GH levels isn't a big deal either because performance is performance. Plus...regardless of what the science may say (and actually Alan Aragon has debunked this myth), most Deadlifters spend 2-4 hours deadlifting. It is normal. You need to rest for 5-7+ minutes between sets to ensure complete CNS recovery in any case. 4 minutes is WAY too little.
Here's an article that will better shine light on this topic:
Ground Up Strength: Ninety Second Rest Periods For Strength? Are You Kidding Me?