foam stopper in secondary

[Bwoe]

Hi,
I just transferred a batch from primary to secondary for dry hopping, and realized that my 2 carboys are of different size at the opening and the rubber stopper won't fit in the secondary (it perches on the top and then falls over...can't get it to stay).
In desperation, I sanitized the foam stopper from my erlenmeyer flask and stuck it on.
My question is whether this is OK for a 1 1/2 to 2 week secondary. My gravity pre-boil and post-fermentation were both spot on, so I don't expect more than .003 change from here, so i'm not too worried it'll pop out.

Thanks for any advice.

 

[SweetSounds]

Cling wrap or tinfoil - Then hit up the LHBS for a proper stopper

 

[brewingkitty]

i used one for 2 weeks on a secondary and it oxidized hard core. overnight wont hurt, but i would get a universal bung asap.

 

[munklunk]

Oxygen = bad. Get a stopper fast.