On 0.2.5e, the following message is printed to stdout whenever a cart containing any arbitrary meta section is run:

$ pico8 -run test.p8 
codo_free fail 21 0

test.p8:

pico-8 cartridge // http://www.pico-8.com
version 39
__meta:foo__
bar

Carts seem to run fine, so there don't seem to be any other negative effects.

Thanks @ridgekuhn, this is fixed for 0.2.5f. It was a benign bug in memory allocation, but potentially dangerous in future versions.

Thanks @zep! :)