Advice needed: comparing two parts
Making an 100nF/10V X7R in a tiny 0402 for $0.002-0.003 is close to bleeding edge. My take is that Kemet is an older U.S.-based company and they simply have not mastered it yet. They do have competitive prices on 0603 parts. 

Since you have the choice of many well established Asian companies you're probably fairly safe with that size - Samsung (Korea), Taiyo Yuden (Japan), Murata (Japan) and Yageo (Taiwan) all have competitive prices in your one-off quantity (one lone reel is not reely a large quantity). If you're not buying for mass machine production, 0402 is not pleasant for hand assembly- 0603 is worth the small difference IMHO.