Yes I had spotting at 28/29 weeks and also was sent for overnight observation @ the hospital. They were concerned about preterm labour or placental abruption - and they took it very seriously even though it ended up being nothing. Definitely better to have it checked, and when I went no one made me feel bad for going in, I actually didn’t want to stay overnight and both the OB at the hospital and my midwife told me I needed to stay.
If you can - take a picture of the spotting to show them when you go in because they’ll ask you to describe it in detail, which I found difficult because I didn’t take a close look before flushing it. So a picture could help them and you. But yes at the very least call your doctor and they’ll tell you what to do. This is what they’re there for.