While driving on the interstate at 70 mph the other day I noticed the Temp gauge had crept up almost to the 3/4 line. When I slowed down to 55 mph it settled at the mid line (normal?) and when I got off the interstate and slowed to 40 mph it dropped to the 1/4 line. The swings in the gauge were mph (rpm) dependent. Ive only had the 2001 LX470 for a couple of thousand miles. Maybe what I observed is normal but it seemed odd to me. I would appreciate any comments and if this is indicative of an emerging problem any fixes would be appreciated. Thanks much