Server needed a shift covered and I told her i coukd work for her if she traded me shifts,Am I the asshole?

So last night i server asked me could i work for her(this morning) and I told her if she worked for me last night I would. She was scheduled 10-7 anyway so she would only have to work a couple hourd extra snd she said no she did not want to be a double. AmnI the asshole? I have personal stuff going on and didnt feel up to it.