I dropped from 130 rep to 120 with no notification. I require some sort of feedback as to why this happened.
You got -2 for a downvote back in June, which was the last activity your reputation history showed until yesterday. Yesterday you deleted a post, resulting in another -8. I don't think you can see that deletion in your reputation history, but you pulled the trigger yourself so I trust you know which one it was.
When a post is deleted (or disassociated), then as far as your reputation history is concerned, it is as if it had never given you rep. Instead of seeing "-8, post was deleted", the entries that gave you the +8 in the first place disappear. If the post was recent you can check the "show recent deleted posts" box on that page to see them, but this doesn't affect older posts. You can see some more-detailed raw data for yourself at https://workplace.stackexchange.com/reputation.