I don't know about Lamplight specifically, but in general, I don't think you can count on any venue doing anything special for birthdays (unless you pre-order a cake or something along those lines). There are so many special days (birthdays, anniversaries, etc.) being celebrated at DL on any given day. At best, you can mention it when you check-in and wear a birthday button, but even then the response might be nothing or a simple "happy birthday" wish from your server.