This is pretty basic...first Mustang. I recently changed out a brake light. 4057LL Sylvania bulb (spec). I noticed areas on the bulb (contact section) and the socket were discolored as in burned. The culprit is heat from the bulb. However, I'm wondering if this is normal or if there is a problem? This is not the case on my other vehicles. Thnxs. PMAP