Sounds like a defective keyboard. Does your MBP have coverage? If so, any Apple Store or AASP for service. However, before you go down that road: Some MBP/MB models also had a keyboard firmware update available via Software Update - see if this applies to yours, and if it does, apply it. (This firmware upgrade fixed a number of issues with certain MBP keyboards. You can also check under Applications > Utilities to see if this keyboard firmware update is already on your computer, but just needs to be run and applied.)
Mac mini (Mid 2011) 2.7 GHz i7, 8GB RAM, Crucial M4 256GB SSD + 500GB + 1TB FW800 OWC Mercury Elite Pro mini
iPhone 4S • iPod nano 8GB • Sound System Audio Engine A2 • Display UltraSharp U2412M 24"