Hmm. I haven't heard anything about that. How would they even know?
The GPL (v2 anyway, unsure about the others), forbid placing any restrictions on the rights to modify and use the software.
As running modified applications on iOS requires a Developer License from Apple for a fee (and associated additional Terms), some believe that the GPL is fundamentally incompatible with the Apple App Store.
Any license that imposes a similar condition (other GPL variations etc) are also likely to be incompatible with the App Store.
Disclaimer: IANAL.