Help!: walking pace is off

It seems like the calculator for determining your walking pace has been off ever since the site changed. I've been using this since the end of August and was impressed with all of the things you could do. At the same time, I maintained my own log in Excel. When the pace in Excel started to mismatch the pace from mapmywalk, I double and triple checked my math & verified that the calculator in mapmywalk isn't working quite right. The distance is fine, but the pace is wrong & there seems to be no pattern to the error. I tried to find a way to notify the site administrators, but couldn't. I'm trying this forum to see if anyone else noticed the problem and has an idea what may be causing this strange problem.