Problems with portupgrade libreoffice

[Walter Hurry]

FreeBSD 9 on x86_64.

I am in the process of doing a portupgrade on libreoffice (from 3.4.4 to 
3.5.2.5). During the build it has (so far) errored out 4 times, in the 
following modules:

vcl
framework
sfx2
tail_build

Each time, it told me to go into the subdirectory, do a gmake clean and a 
gmake -r there, then return to the top level and rerun make.

This I duly did, but to my surprise, each time I ran the gmake -r, it 
completed successfully.

When the top-level make finally succeeds, I intend simply to rerun the 
portupgrade, on the theory that seeing everything already made, it will 
just do the uninstall/reinstall, sort out the dependencies and so forth.

Q1) Is this a sensible approach?

Q2) Has anyone else seen this? What is going on?