Can someone please explain how I'm the jerk in this situation?

So I've been walking around like this since Saturday

Not the end of the world, and I'll recover but it is hard not to notice I am currently one handed

This morning, someone asked me to move a couple computer components around because I'm the "IT person" (which I’m not)

I stared at the person blankly

The person stared back

Can you do it today I was asked

I continued to stare in muted fashion at said person

The person stared back

When I still said nothing, the person said to me

So I take this to mean you are unwilling to help?

No I said, I’m willing to help, are you?

Their response?

You know, you really should try to be a bit more considerate when people reach out to you for help

You’re right I said

So I crawled around on the floor undoing cords and cables then asked the person to move the tower and monitor for me

Can’t you just sort of push it?

Well I said, it’s a bit heavy and I’d rather not drop it or you know, hurt my hand any more than it is

Never mind, the person responded in that tone that says I don't even know why I bothered asking you, I’ll get someone else to do it for me

I just need you move the tower for me  

You said the tower AND monitor 

Yes, I did  - you're right - sorry 

Never mind, I'll just get someone else

Can someone please explain how I'm the jerk in this situation? 

Totally fine if I am, I just need to know the logic behind the argument  

Oh and by the way, I moved the tower myself...AND the monitor...no one has yet to notice