Thanks for the responses. I believe you guys are correct. It is inherent in the MP3 specification that it add a tiny gap.
But, I thought someone posted a utility which would allow you to clip out the gap and re-save the file.
The reason for my concern is... I had a file approved but, the reviewer indicated it was not a loop. The .wav file is indeed a perfect, seamless loop. The mp3 preview however has the a fore mentioned gap. This is the only reason I can interpret that the reviewer would indicate it is not a loop.
I have sent in a support ticket inquiring. I'll let you guys know if we figure it out.