Has the rule changed about footballers exposing a slogan

[Gromit]

From under their shirt on scoring.

I noticed Carlis Tevez pulled up his shirt at the Community Sheild to reveal a message and again today.
On each occassion he was not booked. I thought this was a yellow card offence, so has the rule changed, or are they doing something to avoid the card?

[Jeza]

I think as he was wearing an undershirt and did not remove his top shirt it is okay. He did not bare his chest.

[factor-fiction]

I think he only lifted his shirt up a little bit so the ref didn't see the slogan whereas Nasri revealed his Eid Mubarek message and was booked