In panel-plugin/wormulon/linux.c in the function checkinterface the system function if_nameindex() is called to obtain a listing of interface names. According to the documentation for if_nameindex, the array returned by if_nameindex is supposed to be freed by calling if_freenameindex. This code appears to fail to do this.
Fixed in CVS. Release 0.3.2 should follow soon. Just for interest: How did you find this bug?
I like reading source code. :-) Seriously, for the modemlights plugin I needed to figure out how to determine whether ppp0 was up. Since the netload plugin was clearly doing that, I browsed through its code, and found its use of if_nameindex(). I then checked the documentation to see whetehr I can use that... So it's not as if I noticed some strange behaviour. That's why I set severity and priority to low. (Well for teh latter I also checked that the code was only called once.)