ai research -- ai research overflow

   I have noticed the ai (on skill level normal) will sometimes not be awarded a new technology when it has the required number of bulbs.  It can happen that the ai has more than the necessary number of bulbs for a tech, and then a turn later it has still more bulbs but no new tech, and so on.  Both via an embassy and by taking the ai player, I have seen the ai go hundreds of bulbs over the requirement for The Republic and Gunpowder, for example.  I am running 2.06 (blush) but I haven't read anything about this issue in bug reports, the mailing list archive, the docs.
  The especially baffling thing is that it doesn't always happen.  Sometimes research proceeds normally.  Is this some kind of handicap?  If so, why does it apply on skill level normal?  I thought I would ask before upgrading to 2.07 (blush again-- slow modem) and/or digging through the code.  Cheers!

Jonathan Landis