Does getting aroused count as relapse?

No, but I'd say it's a form of peeking and not a good idea.

 

It sounds like what you're going through right now is what's known as the Flatline. It is a period after quitting PMO in which your libido will disappear for a while. It is completely normal, and for some it even helps train yourself to stay away from the material and thoughts that led you to PMO in the first place. The first danger of this is 'testing the waters' to see if it's an issue - do not do this. Some will consider this peeking / edging and a relapse. Is it one by definition? Well, that depends on a few factors.

What are you goals for abstaining from PMO? Are you trying to quit P? Is it an addiction? These are questions for you for yourself. If what you did to stimulate arousal was something like, say watching the material, then perhaps it could be considered a slight relapse. That's a difficult way to look at it - but you have to think about it from a brain chemistry perspective. Are you purposely firing up the same pathways that you are trying to fix via No PMO? If you are, and you know if you are, you might consider it as such. There's not a lot of concrete 'that's a relapse' answers, because unlike a substance addiction, this has no palpable measurement. (at the moment, anyways.) You can't get tested for PMO, for instance. That's why it's important to think of how it applies to your situation and what you're trying to accomplish.

There are some articles on YBOP (Your Brain on Porn) that better go into the definition and effects of a flatline, but that's the gist of it. My personal advice coming from my own experience would be to not peek nor seek out arousal, especially this early in a reboot. You will be fine, it is a natural part of it that most of us encounter. Some for longer stretches of time, some for shorter. I believe I shortened mine (And this is my case, it may vary for others) by making additional major healthy changes to my life in regards to my own health. It was difficult for a week but the positive effects showed up in spades, and they're what're helping me restart and keep going despite a slip-up. That's my two cents about it.

Keep up the good work, you've got 9 days so far. Take it one day at a time - you only have to be clean today. And then you just start again the next day. All the best!