I'm being polite and expecting someone to decline an offer for us to split the bill
What gives you that impression?
The other person has been hinting.
Don't be rude about it, but tell them to come out with it. Making you wait for a response is inconsiderate, even if they're being indecisive.
It's fine, I'm OK with it.
If it does happen, and it's not a big deal then it should be okay.