I checked out the memory leak article you referenced. It gives no code nor evidence of any kind that it is a perl problem. That being said, there may or may not be a memory leak in this situation.
In the short time I've been a member and seen the trepidation surrounding perl apps, I've never actually seen any "perl has a memory leak and it's ruining my program" posts substantiated. Mostly just unfounded suspicions that could be traced towards what the other monks suggested- inconvenient scoping and non-threadsafe modules that could be keeping references to your hash, thereby foiling the garbage collector.