new glock 26, question about something that looks odd in the receiver

this is a NIB glock 26 i purchased today-

in the receiver, right in front of the slide lock lever...

i see a thin metal "U" that starts halfway up the plastic block holding one front metal slide tab...and the thin metal loop then goes down, across the bottom and then up the plastic block holding the opposite side metal slide tab, but is not nearly as visible. the plastic molding around it is not consistent and the loop is exposed in a very uneven manner.

so, i'm curious...is this metal even supposed to be exposed? it's not on my 21, but you can sort-of see where it would be as it's got some contrasting plastic raised a bit on the mold. i know the 21 is alot different than the 26 for obvious reasons.

sorry for big and unfocused pics but it's late ; )
the last pic is of my 21 receiver




my 21 for comparison


thanks