Problems with a Backup Via Rsync

{{{I had a stroke in 2011, and I am brain-damaged and my short term memory is broken}}}

I have a 1/2 TB flash drive and once a month, I backup my music library to this flash drive, as I need all of my ID3 tags to be complete and correct. {yes, I am somewhat anal-retentive}

My rsync command is:

rsync --archive --delete --verbose --progress --stats {source} {destination}

Now, my {source} is approximately 184Gb, and it has generally worked as planned, but today it took alot longer than usual, and the {destination} was approximately 300Gb.

QUESTION:

I am asking how this has happened, how is the {destination} about 1.6 times the {source}

Are my rsync parameters incorrect?

{PS: yes, I really do the extended versions of the parameters}

Thank you for reading my question, and I would appreciate any assistance in this matter.

Have a great day!