Yeah... I wouldn't make it a gigantic deal, but I would mention it. You can do the "oh, silly Daddies!" tactic.
If it doesn't change, I would just keep doing what you are doing. Make sure you have an extra, properly fitting pair and do a quick change.
I know my kids all go through awkward phases where it seems like no size properly fits them. Or that only one pair of pants fits right. I would not make it a big thing, because it could be a money issue?