LaTeX A4 paper format in Debian Wheezy

On my LaTeX-installation in Debian Wheezy (testing) pdflatex „suddenly“ refused to create PDFs with A4 paper format which always worked well for the last years. Just setting the a4paper option wasn‘t sufficient anymore. I now have to \usepackage{geometry} – otherwise it would create a PDF in „letter“ format. For me it seems like there were some changes in the configuration which packages are loaded automatically by default.