The system is designed to have votes represent only the post at hand - and have nothing to do with the person's other actions on the site.
- Automatic vote invalidation happens outside the tools and visibility of elected moderators. We know how it works but do not get notified when it triggers. We can check a specific user to see if it has happened to them, but we can not even inspect the algorithm used to detect it.
- The site developers are the ones that tune, watch, craft that tool.
As you laid out the actions, it seems that the tool stepped in properly to alert you to the mis-use of the votes, but realize this isn't any sort of permanent penalty. Think of it as a warning if you were speeding on the freeway. The "officer" pulled you over and said - "Glad you're having fun with the voting system, but please slow down."
However, we all recognize, that sometimes a token appreciation seems insufficient for a very generous effort.
Officially, the correct way to transfer more reputation to an answerer is to use the bounty mechanism as opposed to searching and voting for other content. That is a much more direct and transparent mechanism to reward an outstanding contribution.
The site unofficially has a "pay it forward" feeling due to the creative commons licensing. So, you could also just offer a sincere and well phrased comment about how the answer in question really was awesome (explaining why if it's not obvious) and then seek a chance to answer another user's question where you have excess knowledge to share.