Did emails about payment modify the settlement agreement?

One party to a settlement made the last installment payment several weeks late, triggering an acceleration clause that led to more liability.  Celtic Marine Corp. v. James C. Justice Co., No. 13-30712 (July 29, 2014).  The parties had this email exchange after the last payment was due and before it was made, which the party in default said modified the agreement:

A (1-5-2013):  Are we being paid the $91,666.66 to settle this once and for all?  I have lost faith in the agreement from your side.

A (1-7-2013): Are you paying us the $91,666.66 today?

B(1-7-2013): Fri

A (1-7-2013): o/n check correct and can’t u do it Thurs for Friday devl?

The Fifth Circuit held that this exchange did not modify the agreement, for several reasons: (1) the parties had not agreed to conduct transactions by electronic means [citing Louisiana’s version of the Uniform Electronic Transactions Act], (2) prior contracts had been “typed agreements physically signed,” and (3) factually, the email that talks about payment “to settle this for once and for all” was 1 of 15 demands for payment in a “one-sided” set of communications.