No, they won't since you run bitaddress website as offline it should be only generated from your PC and it won't send any keys from your PC to Bitaddress online.
Just be careful to any phishing websites from this list {Warning}: Bitaddress.org Phishing websites
Or better use the opensource one from here https://github.com/bitaddress/bitaddress.org
and Like the o_e_l_e_o said always make sure that your device is clean before you generate private key offline because there is a chance that they can get your private key from offline so once you go online again it will send automatically to unknown/hacker and stole your wallet.
Anyway, can you access the bitaddress.org?
I can't access the website right now it seems they are under DDOS attack?