I'm pretty sure it's a standard message thats been there a while, it only says transactions MAY still be reversed. it's the buyer protection side of paypal - it's why people use it. If the buyer raises a dispute paypal will put a hold on the amount of money it was for while it's sorted out i.e. they claim it was never sent, arrived broken, etc.
Make sure you have have proof of postage and if possible proof of delivery.
Out of interested - what are you selling?