Not an issue, normal behaviour.
Max server memory sets the size of the buffer pool. There's also the non-buffer memory (CLR, linked server drivers, backup buffers, thread stacks, etc). That's allocated above and beyond the buffer pool. It's usually small, but that depends what you're doing. Lots of CLR and it'll be larger than normal.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability