I find electronic ballasts to be tiny bit dicier on the reliability and fussier overall. If there's any kind of short in the fixture that takes the current to the fixture frame, for example, and the frame is grounded.. some will react differently than others. I once had a electronic ballast where it shorted out to ground and that was the end of the ballast. 5 minutes old and it was garbage.
Your GFCI tripping indicates a ground fault to me (ie., current on the ground wire or a current imbalance, or whatever) and not an overloaded circuit. I realize that saying this now is a little like rubbing salt into your wounds, sorry not intended as such: I feel your pain, trust me (nothing was worse than the feeling of reading the warning label on my junked ballast: "Caution! Do not let lamp leads contact ground!") But in the future if your GFCI trips twice in a row like that, stop right there, and don't proceed until you've worked things over and found the ground fault.
I would check your fixture for any loose or pinched wires (you'll have to open it up and examine every wire, every connection). Dollars to donuts there is something.