Can an exhauted memory pool/buffer cause a class to not be found?

A customer has an irule that picks a pool node based on certain criteria. The dynamic pool is set during a

when RULE_INIT { set static::pool_data_group "/Prod/S_pool_dg" }

Then, when HTTP_REQUEST {

...// if checks for cookies, pools, info, etc. //

set id [class startsearch $static::pool_data_group]
//other stuff
}

This was running fine for months on both a production and development LTM at 11.5.0 HF3, then we upgraded the production to 11.6.0 and development to 11.5.1 hf5. After a few days, the production, and later development, starting logging the failure:

err tmm[9129]: TCL error: /S_select_pool_irule - Could not find class /S_pool_dg (line 22) invoked from within "class startsearch $static::pool_data_group"

What's odd is that 40-50% of the time, the unit is logging successful rule hits, the remainder of the time it logs the above error.

I rebooted the production unit back into the 11.5.1 hf5 partition and the errors stopped (since we had not previously tested the production unit in 11.6.0 (don't ask about the logic). The development is still logging the errors, as we would like to determine a fix other than "reboot". Any ideas?

Thanks! Chad