In case no one else gets around to this:
No. Not normal.
We all know there's some shoddy-quality XLR's on the market...but even if they fit poorly, they should still fit. If not - don't use it.
I'm willing to bet a bag of pucks that your XLR (poorly-fitting or not) was forced into the M12's input jack - possibly out of proper position - which would've created the inability to smoothly detach it.
If you need to be reminded to not do that, call your mom and ask her about burning your hand on the stove.