My 89 accord used to do it on hot days also,its probably just dry sockets,you might just try resoldering it.
If you pull it and open it up you can see the cracks around the posts,just clean em off and drop a new joint on em,very easy.I did it the first time I had ever used a solder gun.
At $.50 in solder or $30ish for a new one so its worth a try or at least a look,its easy to tell if its the sockets and 3geez.com has a good write-up on it if you want a better explanation.