Brake lights cause burning smell...?

I bought my 97 Camry not too long ago, and recently realized I didn't have brake lights. At
the auto store I gave them my make/model/year and they gave me Sylvania 357LL bulbs.
Went to put them in and I realized there were no bulbs in my brake lights whatsoever, just
empty sockets. Put the new bulbs in and they worked... drove away.  

But then every time I stopped for more than 5 seconds at a red light, I would start
smelling burning plastic. The smell was coming from the trunk/brake lights area. The gray
sockets (where the lights are put) are slightly burned looking, a rusty brown around the
edges. (I believe they looked like this prior to the new bulbs.) I took the new bulbs out.
Still getting that smell slightly when I start up my car but it's less and less each time.

Any ideas if it's the socket or the wiring?
Should I try a lower wattage bulb even though this is the exact bulb I need?