Python GC_Script Question

I've got a question on my python script: https://github.com/basmith89/BrianPLP599_scriptsn_such/blob/master/Rosalin_GC_content.py

So this file takes in a fasta file and stores the the seqID into a list and the sequence into a list.  My main question is why do I need to .append once more outside the loop on line 30 to ensure that the last nucleotide sequence is added to the list.  The last seqID is placed its list but not the last sequence.

-Brian