PHP Fatal Error caused by Magento

Question

So I'm checking my error logs and notice a bunch of these:

[20-Aug-2010 15:06:32] PHP Fatal error: Allowed memory size of 262144000 bytes exhausted (tried to allocate 16 bytes) in /home/website/public_html/lib/Zend/Db/Statement/Pdo.php on line 294

So I know that this has to do with the memory size set in php.ini, but it has been set to 250mb, which seems pretty high already for a VPS. There's quite a few of these errors, however front end performance is not affected.

Is it possible that I'm leaking memory somewhere, or is this a minor error?

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Update: this is on a myriad of files:

app/code/core/Mage/Core/Model/Config.php

app/code/core/Mage/Eav/Model/Entity/Attribute/Abstract.php

lib/Zend/Db/Select.php

Mostly on models it appears?