This may be an issue with R-Forge's build server; I have the same issue with another package where a dependency is no longer available but which is available on CRAN and builds/checks OK there. My package checks OK on Linux but not on R-Forge. When I submitted it to CRAN it passed their checks too.
With changes in the last version of R to be released, package libraries have needed to be rebuilt. This may be related to the problems on R-Forge?
Anyway, Suggest you file a support ticket or email the R-Forge team to enquire. If that package builds/checks OK on your own computer, then it is probably safe to submit to CRAN. If you want to be doubly sure, perhaps submit the package to Uwe Ligge's WinBuilder service to get an independent compile/build/check. If that works OK, then you can be reasonably sure your package is OK to submit to CRAN.