Yes, I myself today literally had that happen with my own knights. I also think that the following needs to be done to better balance wizards.
1. They need a population cap increase based on their level. Wizards increase in power substantially over time more so than any other unit in the game based on their spells having a minimum level requirement. All in all, by level 50 which unlocks their 5th level spell for use once researched should eat 25 population cap. Yes, this is a lot, but it would also limit the ability to use 2 wizards in one army, where as quite a few at this time run a calm and deep wizard or calm and wave together with only 10 cap points giving a lot of power.
2. Reduce their regeneration each upgrade from +2 to +1 to a max of 1/2 of a hero's cap, this way should the hero's top regeneration ever be altered theirs would be as well.
3. Remove the AoE follow ability (Which is already being looked into).
The above would also most likely require a look into dragons shortly after with Royal and Red dragons possibly needing a pop cap increase as well, but they don't have near the utility as the wizards do at this time.