There is nothing you need worry over. If it ever comes online it will automatically lock unless you removed it from the Find My Phone/Mac list. But for you to have done that you first have to remove the lock instruction or upon trying to delete the device acknowledge what you are doing will result in killing the lock instruction.
What To Do If Your Mac Is Lost Or Stolen
If you activated Find My Mac before it was lost or stolen, you can track it only if it is connected to the Internet. What you cannot do is track your computer using a serial number or other identifying number. You cannot expect Apple or anyone else to find your computer for you. You cannot recover your loss unless you insure your device for such loss. It is not covered by your warranty. Be sure to report the loss or theft to the local police. Have the serial number handy. If your Mac is found it cannot be returned to you if you don’t have the serial number and proof of purchase.
Find My Mac can be used from Find My Phone at iCloud.com and via Find My Phone on your iDevice.
The following is a sampling of third-party anti-theft software:
1. MacTrack 7.5.0
2. VUWER 1.7
3. Undercover 5.1.1
4. LoJack for Laptops
5. Hidden 2.0
6. Prey 0.6.2
If your iPhone, iPod, iPod Touch, or iPad is lost or stolen what do you do? There are things you should have done in advance - before you lost it or it was stolen - and some things to do after the fact. Here are some suggestions:
1. Reporting a lost or stolen Apple product
2. Find my lost iPod Touch
3. AT&T. Sprint, and Verizon can block stolen phones/tablets
4. What-To-Do-When-Iphone-Is-Stolen
5. iCloud- Use Lost Mode
6. What to do if your iOS device is lost or stolen
7. 6 Ways to Track and Recover Your Lost/Stolen iPhone
8. Find My iPhone
9. Report Stolen iPad | Stolen Lost Found Online
It pays to be proactive by following the advice on using Find My Phone before you lose your device:
1. Find My iPhone
2. Setup your iDevice on iCloud
3. OS X Lion/Mountain Lion- About Find My Mac
4. How To Set Up Free Find Your iPhone (Even on Unsupported Devices)