Color of Card Backs

[PriusGuy2004]

Hello. I have both the "Munchkin" (1st edition, 24th printing ... published January 2013) and "Munchkin: Legends" (1st edition, 1st printing ... published April 2013) base games. I recently purchased the 112-card expansions "Munchkin 3: Clerical Errors" and "Munchkin 4: The Need for Steed" from Amazon.com. They just came in the mail today. When I took out the cards for "Clerical Errors", I noticed that the backs of the cards (Doors and Treasures) are a slightly different shade compared to the cards I have for the base games. If I mixed this expansion with either of the base sets, I could easily tell the sets apart. Should this be a concern? Or, does everyone have this issue? I'm wondering if I should try sending this back to Amazon.com and asking for a replacement in the hopes that I might get a set that matches the base sets? Or, I was wondering even if I could just visit my local board game store in town where they have Munchkin and ask if they might consider exchanging? I'm just not sure what to do. What do you all suggest? Thank you, in advance.