Mysterious sopc_altera_pll directories in my home directory

I have been noticing that empty directories are getting created in my home directory when I run ip-generate. The directories have names of the form sopc_altera_pll<secs><digits> where <secs> is the current time since Jan 1 1970 and <digits> are just random digits (could be sub-seconds times). This is with the Quartus 14.0 and running on Linux.

Has anyone else seen anything like this?