This is due to the DLC being prepared for the game, and they already coded the assasignments and new equipment in. It is kinda of a glitch but everyone who has premium, (not to sure about those who don't have it) can unlock them already. Usually the "trigger" to seeing the assasignment, is to do part of it and you can only see it after a match ends. At the score screen you can click the different tabs to see your overall score, unlocks coming up, and assasignments. If you like I can post the requirements to unlock the guns/equipment here:
It really isn't an issue, as it really is leaked content.
Spare time Sniper
- Assault Rifle ribbon x3
- Get 20 headshots with Assault Rifles
- Reward: AR160
Packing a Punch
- Destroy 20 boats
- Reward: SR-2
Swiss Cheese
- LMG ribbon x3
- Destroy 3 vehicles as Support
- Reward: AWS
Always Deadly
- Sniper Rifle ribbon x3
- Get 5 kills with C4 on NS maps
- Reward: SR338
Curve Ball
- Get 10 kills with an Impact Grenade
- Reward: SW40
Multi Tool
- Get 10 kills with UGL Darts
- Get 10 kills with UGL LVG
- Reward: M320 3GL
Death from Below
- PDW ribbon x3
- Destroy 5 attack air vehicles with Rocket Launchers
- Reward: AA Mine
Source: http://bf4only.com/news-battlefield-4/83-battlefield-4-naval-strike-dlc-weapons-and-assignments-leaked