Is this normal after an offer

Put an offer on a house (offered it's asking price) yesterday afternoon. Their estate agent was open on bank hol and had been talking to us through the day, until the offer, which was our in quite a bit before they closed. We are FTB, we were advised by their agent that the sellers had a home to move into so wanted fast movement.

Didn't hear from EA after offer yesterday or early today, even for acknowledgement received, but emailed and called a few times leaving messages to ask if offer was even received by them. Eventually get a call back at 2:30PM. Agent says the following:

- We are the first offer, sellers are grateful for our offer, but are going to wait a bit to see feedback/if there are any more offers from other viewers

-The sellers are also still negotiating on the property they want, their offer hasn't actually been accepted yet, but because they now have our offer on their house it puts them in better position.

- He said not a no or a definite yes at this point. But think that's just because it's only just gone on the market, and he said they were pleasantly surprised to have an offer so quickly.

- They are going to keep us informed this week (?).

Am I reading this correctly that we are essentially being used to start a bidding war and they are holding out to see if they receive another offer? Am I right in assuming this is probably their EA telling them to wait so they get more? Am wondering how long people who have had similar have been patient with this sort of thing. We can obviously go and view other properties and find something else this week too if we wanted to, so wondering when to ask for an actual response to them. We don't feel the house is worth much more than asking price, and the market is moving slowly where we are looking, so this felt a bit unexpected and our mortgage advisor agrees it is an interesting move by them.