Just today during a walk around I notice water and ice build up just at the tip of the wing where the winglets are fastened. At first I thought this was fuel. Opon closer inspection it was found to be water / slush. I checked the other wing tip and found the same accumulation. this particular aircraft is a 737-300 with the winglet mod. I walked over to the adjasent gate with a new 737NG aircraft and noticed the same thing. Water and ice accumulation is bad news. Asking around the shop no one knows of a problem, then again no one has looked for it. Nothing documented in our GMM or other references.
Anyone on this board notice this problem?