My in laws live 3 hours away and have been to visit us every month since baby was born! We have went to visit them once as well. I would say you’re right to feel that way!
My in laws live less than an hour away from us and have only seen my daughter 5 times in 6 months, it surprised me as before she was born they kept making comments about how it was going to kill them not seeing her every day so I expected to be making excuses for them to not come every week. I’m half glad as they irritate me a bit but at the same time pissed they haven’t made more effort as they see their other granddaughter at least a couple of times a week and they’re only 10 minutes closer to her! Their loss in my eyes. How many hours is a few hours?
Yes 100% my in laws live 4 hours away and have tried to come up every 4-6 weeks to see her. They shouldn't be expecting you to go to them as you have a baby, they should definitely be making the effort to come and see their grandchildren