Authentic is an auctioneer and retailer of vintage comic books. It recently acquired possession of a pristine copy of Action Comics No. 1, the first appearance of Superman in 1938. Gallery is a museum and retailer of unusual and rare comic books. When it learned of Authentic's recent acquisition, Gallery sent Authentic an email saying, "I must have it! What's your price?"

Authentic responded by emailing, "If you're referring to Action Comics No. 1, one similar to mine just sold at auction for $3.2 million."

Gallery replied, "Ok, to be fair, I'll give you $3.5 million for yours."

Authentic answered, "No, that's a little lower than I was expecting, and the comic hasn't been appraised yet. But I'll sell it to you for $3.75 million, as long as it appraises for $4 million or less. Think it over. You have about a week until it'll be appraised.

That day, Gallery sent to Authentic a signed check for $3.75 million. In the memo section of the check was written "Action Comics No. 1." A few days later, the comic appraised for $4 million dollars. On the same day of the appraisal, Collector offered Authentic $5 million for the comic book and Authentic accepted the offer. Authentic had not yet received Gallery's check and sent Gallery an email saying, "As I have not heard from you, the deal if off. I'm selling the comic to Collector for $5 million."

Was there a valid contract between Authentic and Gallery? Fully explain.