I made marshmallow fondant about a month ago. I've kept the leftovers wrapped in suran wrap in a ziploc bag and in a tupperware. I colored a chunk of it purple. I went to check on it the other day and the inner portions were purple, but the rest was blue!
Why did this happen?
Is it still good?
How long does marshmallow fondant usually last?
Did I store it incorrectly?

Thanks in advance!

Purple normally fades very quickly.

Yes its still okay to use. Like grandmom said, purple is one of the colors that fades quickly.

http://cakecentral.com/cake-decorating-ftopict-699914-fading.html+purple+fondant

http://cakecentral.com/cake-decorating-ftopict-695546-fading.html+purple+fondant

http://cakecentral.com/cake-decorating-ftopict-676862-fading.html+purple+fondant

Thank you! Next time, I'll try to make sure to search through the forum first before posting a question :/
Can anyone tell me what I can do with my existing purple/blue fondant? Can I just re-dye it purple or am I stuck with what I've got?

...add a little red. Red and blue make purple.

Purple is not a stable color and tends to turn blue.