That is exactly the way I sit at my desk & lean on my left elbow. The last few days I've had this warm sensation come & go quickly on the back of my left thigh. It is the strangest feeling. However, reading your post made me feel much better & I guess I need a better chair & posture. I've never sat up completely straight. Amnyway, I'm going to try to sit up straight & see if that helps. It's not painful, just annoying. Thanks for posting.