Is it normal for a buried implant to be showing a little through the gum?

Just because a buried implant becomes exposed does not mean it is failing, but it is very important that if the implant is only partially exposed, have the dentist that placed the implant fully expose the implant by attaching a healing abutment. Studies have shown that partial exposure of an implant if left as is will lead to bone loss around the implant. 

Being able to see the implant through the gum tissue is not necessarily a sign of implant failure. (If you have other symptoms such as pain and swelling, there may be a slightly higher chance of failure.) If you have any concerns I would encourage you to contact the doctor who placed the implant. It's important to note, if a little bit of the implant is exposed, keep the area clean for better healing.