Hello Cathie,
 
We recently lowered the minimum resolution and dimension requirement for new images.  This change will not affect any of your existing cards.  
 
For best results we still recommend creating images that are 1500x2100 pixels at 300dpi.  It looks as though all of your current images meet this recommendation, so we would advise against making any changes.
 
Please let me know if you have any additional questions.
 
Shaun