When you were low-bid on the house the first time around what did you tell the agent? Are you a serious buyer? Have you actively been pursuing properies with the agent with a purpose to buy?

As for obligations, there are none to inform you of the status of a property weeks later of which you longer have an offer on.

“So, I wasn’t actually harmed this time.”

To be frank, that sentence strikes me as you’re looking for a reason to find fault.

To be doubly frank, the agent didn’t call you to put a bid on the house you previously had low bid on so basically the agent didn’t want to waste more time on a low bid with in their mind little chance of getting accepted. If you had them on paid retaining it might be a little different, but otherwise, you’re burning their cash and they don’t think you’ll close the deal.