I don't think it's supposed to do that

So I started poking into the front window sills a little. After we tore out the sill, we found that it was leveled by inserting chunks of brick under it, then caking lots of mortar over the whole thing. Well, it worked for a long time, so I'm not arguing.

So I bought this vinyl windowsill profile to put in there, and decided to chip out the mortar to make room for it. It was kind of loose, though.
By the time I got done cleaning out loose mortar, the top row of bricks was out. So I think that probably needs to be fixed...