Were they lying?

[Bienes Raices]

I made an offer through the short sale's listing agent. Early the next morning I received an email that the seller had not accepted my offer, and that they had another offer coming in. They wanted my highest and best.

It seems kind of suspicious to me--I wonder if there really was another offer. Is this just a technique to get the highest and best out of someone before submitting the offer to the bank?