The short answer as to why you specifically were tagged, is because you own enough DHEDGE tokens to be added into an upvote round after posting.

The rest of the answer is:

It was decided when upvote rounds were added, that DHEDGE holders should know where they stood in a round. Instead of adding a comment to each post in the round, a single comment is added to the DHEDGE daily report with the full rounds results.

This reduces spam comments on users posts, it draws DHEDGE users to the DHEDGE daily report, it advertises that people are now receiving upvotes for their DHEDGE, and shows exactly who received what share.

If a user doesn't have enough DHEDGE to receive an upvote in that round, maybe they decide that they want to be in the next round. They might buy some DHEDGE off the market, or maybe even delegate to @dhedge and receive DHEDGE tokens paid daily. If they buy, this increases the price of DHEDGE, if they delegate, it increases the value of the vote users receive.

So some type of "advertisement" is a benefit to the holders of DHEDGE, this was decided to be a good middle ground for that advertisement to take place. If someone complains that they receive an extra notification every now and then, and they have enough DHEDGE or HIVE rep, I'll wright in a way for users to opt out.