Q:

How can I re-trace where the +1s in the recent achievements icon come from?

Perhaps I should go to chat for this, but I can imagine more users have this issue. How can I re-trace where the +1s come from in the reputation-change icon on top of the screen? 

Firstly, does it have to do with the rep penalty accompanying downvotes being reversed?
Secondly, I am not able to quickly re-trace why it has been reversed. If it is through post-edits by OP, I find it particularly important to be able to go back to the post and upvote if the changes are good. If the reversal is due to post deletion, it is still important to go back to the post, as (my) downvotes generally are not meant to urge OP to delete it. On the contrary, to me it is a push to post-improvement and if OP deletes it instead, I may want to follow up on it.

Can anybody provide guidance on what these +1s mean and how I can retrace them to their associated posts?

A:

This can be found it relatively easy: Go into your profile and click on reputation. There you see you reputation listed on a daily base and also for which action you gained (or lost) reputation. 
+10 are upvotes for answer
-2 are downvotes you receive
-1 are downvotes you "give" to other people (so downvoting costs you something, too)
+1 are reversed downvotes either when the downvoted item is deleted or when you take back the downvote (after an edit for example).
The complete list of reputation gain/los can be found here.
Note that the list in your profile might lag a bit behind, since the process of keeping it actual is not running every second.

