Sorry, me again :(
We've made some changes to the code that handles those numbers, so now, we only show (and count) the oldest message in a thread that was addressed to you.
Today I've received few messages adressed to me. 2 of them were from the same thread and there were totally 2 messages to me in that thread. There were also 2 messages to me in another thread, but only the oldest was shown as "unread adressed to me".
Just to let you know. That's not important at all.