Missed period....

So I've had my skyla for almost a year and a half now. I haven't had any ACTUAL sex in a while (since April really, I fooled around in August but didn't get any p-in-v action, much to my chagrin) so I'm fairly certain I'm not pregnant. I had a little teensy bit of spotting in the beginning of last month, but I would hardly call it a period. I'm just a little...weirded out? I had just had almost a month of bleeding, and now it's been a long while without a period. Is it normal to miss/skip/only spot with an IUD?