To reproduce create an empty project with the following build.sbt
scalaVersion := "2.10.1"
libraryDependencies += "org.scala-lang" % "scala-reflect" % "2.10.1"
libraryDependencies += "org.scalatest" %% "scalatest" % "1.9.1" % "test"
Running update or compile generates a warning
[warn] Potentially incompatible versions of dependencies of {file:/Users/jdolson/src/test/sbt-warn/}default-b92950:
[warn] org.scala-lang: 2.10.1, 2.10.0
Given the assumed binary compatibility between 2.10.0 and 2.10.1 this warning is unnecessary (not to mention massively annoying if you have a lot of subprojects).