file timestamps in a git tree

[Saulius Krasuckas]

* On Wed, 31 May 2006, Marcus Meissner wrote:
> * On Wed, May 31, 2006 at 12:55:02PM +0300, Saulius Krasuckas wrote:
> > 
> > $ git rebase master ugly_hack
...
> > $ git checkout master
> > $ make
> > Makefile is older than Makefile.in configure, please rerun ./configure
> > make: *** [Makefile] Error 1
...
> > I thought git would reset all the file timestamps once I switch to 
> > another (master) branch...  Am I wrong?
> 
> "Makefile" is not in git, so you need to run ./configure anyway?

Well, yes, but what is changed in the tree after I checkout master branch 
back?  If nothing changes, why make is complaining?