I know this is bloody stupid but these little things just give me headaches 
I know some people on here have followed my previous posts about DP and my parents not getting along. They don't see each other and don't talk due to working together in the past.
My AIBU:
I'm going to see my parents today with DS, my DDad text me yesterday asking if I could bring DSs bike seat as they were thinking of going for a ride.
The bikes are kept in a garage at DPs office (he's self employed). I asked DP if the bike seat is hard to take off and he said it's a bit of a faff as its screwed on etc. and asked me why - I told him DDad asked as they wanted to go for a bike ride etc. Immediate awkward/weird atmosphere.
I asked DP if he's in the office in the morning so I could pop in on my way there and he didn't really reply (about half and hour before this he mentioned that he's in the office most of the day BTW). Asked if he wouldn't mind having a look for me if I come up as I'd like to take it with me.
Again no real answer, I left it for the night I know most subjects re my DPs put his back up.
This morning before going to work he told me that the bike seat is not a good idea, and that I know how he feels about the situation and that he doesn't want to get involved in anything to do with my DP(arents). He also said it would be a pain to take off and put back on. And he said I would probably be unable to do it myself if I came and would then ask him and he doesn't want to get involved. He reiterated he's happy for me to stuff with them etc but doesn't want anything to do with it/wants to be kept separate. I was sat there a bit 
I asked him what he expects to happen and he said they should buy their own bike seat. (DS is two and this will be the first and probably only time until at least next year that they take him for a ride hardly worth the £££s)
He then gave me a kiss as he was getting ready to leave, I just said that this just makes it harder for me and didn't really speak. He left for work.
AIBU to be put off that he's unwilling to even help me if I need it? I understand he doesn't get on or want anything to do with my parents (even though I found it extremely sad and upsetting in the past) but this just seems petty.
Also AIBU to think that expecting someone to shell out for a bike seat that might be used 2 X times a year IF that is a bit crap? Especially as it means that we can't go for a bike ride today as we won't have a seat?
I'm tempted to just go up and try and take the bloody thing off myself but I think I probably won't be able to as I'm terrible at it. I'm just annoyed 