There have been a few threads about this, one of the more recent ones.
http://www.wgt.com/forums/t/245357.aspx
What you are experiencing is a minor display error where your level is advancing normally, but is not displaying correctly on your profile. This is a temporary issue and will be resolved when you earn the Experience Points (XP) necessary to advance one level further.
For example, if your profile indicates you are level 42, but you have received XP necessary to reach level 43, your profile will once again correctly display your level as soon as you reach 44.
SP, I'm glad it wasn't me accidentally putting my foot in it this time. It was funny and directed at Shoe and Icon, I'm sure it will be seen in the way it was intended.