Why worry, it is still much higher than mine, which is 113MB. I don't have the vrdb enabled so that saves a lot. some log files may have reduced in size, you may or may not have cleared files from the chest, there are many permutations.
If avast is still working as expected don't go looking for trouble that isn't there.
I don't go looking for trouble, unless avast displays errors to the screen I let it get on with it. Had someone not started this topic, I wouldn't have bothered to check the size as to me it really is immaterial.
I also keep my nose out of the logs as they really aren't a great help for your average user, unless avast starts throwing up error messages to the screen I leave well alone.