@TFMoma
OMG YANBU at ALL.
My DH used to have form for this - volunteering me for stuff. Especially when the kids were little, and I worked part time. 'Oh Poppy will do it, she's not doing anything else...' And 'Poppy will take her, take him, do this, do that blah blah blah.' He even used to volunteer me to take his relatives to hospital appointments and all sorts. So fucking annoying.
I would have been pissed off at your DH personally.
It's not 'bad form' for you to say no/refuse, because you never bloody offered to do it FGS. 
Don't be like me when I was much younger - I used to be a right mug - having chores handed to me, and giving lifts foisted on me, and all sorts... Apparently because I worked ONLY 24 hours a week, I had all the time in the world to run round after other people.
The last straw came when DH volunteered me to take someone's kid to school every bloody day. Her hours changed from 9am to 2pm, to 8.15am to 1.15pm and if she was able to do it, she had to have someone have her kid from 7.45am and take him to school at 9am. My kids started school at 8.30am (it was a different school a mile away,) and I would have had to drop them off at 8.20-8.25am, and keep hold of said boy til 9am when HIS school opened the doors.
Wasn't doable (or worth it) for me to go back home, so I'd have been hanging about for half an hour! Then I had work from 11am til 5pm. Because I didn't start til 11am, I had LOADS of spare time apparently... 
DH told this woman I would do it (she was a neighbour,) and I went loco. I said 'how fucking DARE you? How DARE you put me forward without my permission to look after this kid from 7.30am to 9am every morning, and have the responsibility for his welfare, and taking him to school.' 
He was trying to look like the 'big man' by saying 'OH don't worry luv, my missus will have him, and take him for you.' 
He seemed stunned that I was angry, and said 'well WHY can't you? It will be no bother.'
Anyway, I went and told this woman (the next day) that I couldn't do it, and he had no business volunteering me. I said (honestly,) that I didn't want to take responsibility for someone else's child, and that I genuinely didn't want to do it.
She was surprisingly OK about it, and said 'that's OK. I thought it was a bit off for your husband to volunteer you for it anyway, without asking you first. I wouldn't have liked it.' She said 'I would never have dreamed of expecting you to do it, so don't worry!'
In the end, she started dropping her lad off at her mum's! And took the different hours.