Yes, this was the (typically) monthly update to the underlying AVG application. That normally comes in one, or often two, biggly chunks.
The second (or in this case the third) bit is generally much smaller and will often be a 'signature' update for the (anti-)virus files.
So it's easy to download biggly Chunk 1 and think you're up to date - but you ain't. So if you get a much-larger-than-usual AVG download, suggest you click the Update button a second time, and keep on doing so until you finally get the 'Your AVG programme has the latest updates installed and is fully up to date' message.